Bolt Thrust Experiment #3 .22 LR & .44-40

Welcome to the Leverguns.Com Forum. This is a high-class place so act respectable. We discuss most anything here ... politely.

Moderators: Hobie, AmBraCol

Forum rules
Welcome to the Leverguns.Com General Discussions Forum. This is a high-class place so act respectable. We discuss most anything here other than politics... politely.

Please post political post in the new Politics forum.
User avatar
KWK
Senior Levergunner
Posts: 1012
Joined: Fri Sep 07, 2007 10:31 am
Location: U.S.A.
Contact:

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by KWK »

It certainly doesn't seem that it's been 7 years since the good John Kort posted his test results. I know when 3 years ago I read he had passed away that I regretted I had never gotten around to making a basic analysis of this problem, as I had said I would. So in John's memory, here goes (as Nath puts it) some jibba jabba.

To get brass thickness in the case wall, I worked from a photo John posted on another site of a sectioned modern .44-40 case (which he was comparing to an early BP case without a solid head).

Bryan Austin provided here an estimate of the pressure John's load might have generated. His estimate of 7.2 ksi I adjusted upwards to 8 ksi to account for the heavier bullet and charge which John used in his test.

I obtained brass mechanical properties and friction coefficients from the site of Varmint Al, who did a full blown, dynamic, finite element analysis of a .243 firing in its chamber. (Al's simulation is porn for us mechanical engineers. He's a retired stress analyst from Lawrence Livermore labs.)

I estimate that at the peak pressure, the case to .4" from its base was capable of containing the peak pressure without assist from the chamber walls. Above that to the case mouth, I estimate the brass could on average contain nearly half the pressure, leaving the rest to be held by the chamber. The resulting cling (friction) would be around 1300 lb, but the net gas force rearward on the brass was estimated to be under 1000 lb. At that point (0.4" up) where the brass would barely be touching the chamber, there is enough brass cross section to hold 1000 lb without plastically deforming reward, unlike with Al's high pressure .243 Win.

The case walls being blown outward have much less inertia than the entire case moving rearward, so case cling will occur sooner than the base can reach the bolt. My back of the envelope calculation, then, says the cling could hold the case forward, and John's little clay balls wouldn't have been crushed, as he observed.

This is not to say there is no bolt thrust at peak pressure. John's test hints the primer produced a fair thrust on the bolt. Note that over the course of the firing, the primer moved inward in its pocket. Surely the primer's blast moved it rearwards to the bolt face (see Varmint Al's dynamic simulation), then gas pressure shoved the case rearward until cling arrested this motion. I estimated 300 lb of bolt thrust from the primer due to the gas forces acting upon it, perhaps more as the pressurized primer was being forced back into its pocket. (That the primer is a significant factor in bolt thrust can be seen in the analysis done by Varmint Al. However, Al's numbers suggest 150 lb might be a better estimate in this problem.)

edit: I want to emphasize the numbers I came up with are only rough estimates. The calculated spread between the gas force pushing the case rearward and the friction holding it to the chamber walls was not great. A certain amount of luck was involved in the numbers coming out in agreement with John's experiment. :D As is often the case with calculations, the numbers simply indicate whether you're on track to understanding what's going on.

It would be fun to see the results of strain gauges on the toggle links of an 1873 firing that mild .44 WCF load.
Last edited by KWK on Thu Oct 08, 2020 9:34 pm, edited 5 times in total.
User avatar
Sixgun
Posting leader...
Posts: 13077
Joined: Sun Sep 16, 2007 7:17 pm
Location: S.E. Pa....Where Trump is Supported and Common Sense Rules

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Sixgun »

Thanks KWK...after reading that I'm really screwed up. :D ---6


Image
You've Seen Guns For Peace And Guns For War
But You've Never Seen Guns Like These Before!

Image
User avatar
KWK
Senior Levergunner
Posts: 1012
Joined: Fri Sep 07, 2007 10:31 am
Location: U.S.A.
Contact:

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by KWK »

In a revolver, you've seen light loads can leave the primer proud of the case base. (In my S&W Model 12, which has a slightly recessed hammer nose bushing, this creates a real problem.) The explanation for this has been around a long time. The hammer shoves the cartridge forward. The primer's blast blows the primer rearward to the breech face while at the same time holding the case forward. The main charge then starts to blow the case rearward (starting to seat the primer again), but case cling stops the case before it reaches the breech face. Voila: A primer which was flush is now proud of the base.

This happened in John's test, which his clay balls confirm.

A consequence of the primer reaching the breech face upon igniting is that the primer applies to the breech the full pressure of the main charge. Unlike the case, which can cling to the chamber walls, the primer is already on the breech, so there is no cling to reduce the thrust on it from the pressure. Instead, the primer's cling to its pocket actually increases the force on the breech when the primer pocket moves rearward.

My rough estimate is that primer cling could increase breech thrust as much as 50% beyond the gas pressure. That calculation is too crude to be trusted (it ignores time), and a simulation such as Varmint Al did would be required.
User avatar
Sixgun
Posting leader...
Posts: 13077
Joined: Sun Sep 16, 2007 7:17 pm
Location: S.E. Pa....Where Trump is Supported and Common Sense Rules

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Sixgun »

Ok.....when that proud primer is really noticeable is when firing an empty case with a live primer......without a rebounding pin it will lock up.....thank you....(I still had to read it three times)---6
You've Seen Guns For Peace And Guns For War
But You've Never Seen Guns Like These Before!

Image
User avatar
KWK
Senior Levergunner
Posts: 1012
Joined: Fri Sep 07, 2007 10:31 am
Location: U.S.A.
Contact:

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by KWK »

I went back and reworded my post, hoping to make it easier to follow.

Yes, I’d forgotten the example of firing a primer in an empty case. This shows what’s seen in Al’s simulation, that the primer backs out to the breech.
User avatar
Bryan Austin
Levergunner 2.0
Posts: 175
Joined: Sat Jan 08, 2011 6:05 pm
Contact:

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Bryan Austin »

It is only obvious that when only primers are shot, the primer backs out from thrust against the front of the primer picket at the flash hole. As powder and bullets are added, the same thing...this is why our revolvers get jammed sometimes buy using such "Light Loads", light enough to where the case does not back out against the blast plate (or bolt) and re-seat the primer. Once enough pressure is reached, the case backs out and reseats the primer but not enough to touch the case head. Again, as more pressure is reached, the case backs out and the case head can touch the blast plate. When too much pressure is reached, the case backs out and tries to re-seat the primer too late and the primer begins to mushroom out and fill the primer pocket.....primer flattening!
User avatar
KWK
Senior Levergunner
Posts: 1012
Joined: Fri Sep 07, 2007 10:31 am
Location: U.S.A.
Contact:

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by KWK »

There are a number of points which still puzzle me.

I'm satisfied there can be enough case cling to keep the case from crushing the clay under peak pressure. However, as Nath points out, during the rapid pressure drop that occurs once the bullet is out, the pressure in the case will drop to the point cling stops and the case should blow rearward. I'm surprised this didn't happen, or at least more so. That the .44 WCF has super thin case walls must be part of the explanation. The drag on the primer pocket of the pressurized primer must also help keep the brass forward.

Then there's Ackley's experiment with an unlocked bolt in, I think it was, a 94 Win -- and I seem to recall his test has been repeated in the last decade. The numbers I got suggest the primer should have blown the bolt rearward some. Maybe it did; it's been a long time since I thumbed through his book.
User avatar
Bryan Austin
Levergunner 2.0
Posts: 175
Joined: Sat Jan 08, 2011 6:05 pm
Contact:

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Bryan Austin »

KWK wrote:
Mon Oct 05, 2020 8:39 am
Then there's Ackley's experiment with an unlocked bolt in, I think it was, a 94 Win -- and I seem to recall his test has been repeated in the last decade. The numbers I got suggest the primer should have blown the bolt rearward some. Maybe it did; it's been a long time since I thumbed through his book.
Everything puzzles me, you guys should know that by now...lol

Here is a video I made showing the 44-40 primer blast doesn't have enough thrust to move anything. I re-positioned the barrel way out away from the blast wall. I removed the firing pin an inserted a typical punch and tapped it with a blunt object. If this was a "normal" vintage loads, the punch would been sent flying out the back door and the case flying back and probably exploding if it didn't have enough time to fully discharge inside the chamber. I am going to re-position the barrel much closer and work my way up to such pressures. I no longer have the strain gauge attached but I have enough data to try such loads. This, of course, will be moved out doors in a safe location.

https://youtu.be/-yBL4ZRaxJ4



120554910_746015059511933_7531662513658591752_n.jpg
120542089_775378663244478_2484460332074893280_n.jpg
You do not have the required permissions to view the files attached to this post.
User avatar
JimT
Shootist
Posts: 2219
Joined: Thu Sep 06, 2007 5:04 pm

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by JimT »

Great video Bryan.
I am guessing you used an empty but primed cartridge? No bullet?
Suggestion, fill the empty case with styrofoam, seat and crimp a bullet in the cartridge, then repeat the test.
User avatar
KWK
Senior Levergunner
Posts: 1012
Joined: Fri Sep 07, 2007 10:31 am
Location: U.S.A.
Contact:

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by KWK »

You're a brave man, Bryan, or should I use a different adjective? :wink:

That firing pin and hammer have more inertia than the typical lever action does, apparently more than the impulse from the primer can bother. I'm looking forward to your future results; please post them here.
User avatar
Bryan Austin
Levergunner 2.0
Posts: 175
Joined: Sat Jan 08, 2011 6:05 pm
Contact:

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Bryan Austin »

JimT wrote:
Mon Oct 05, 2020 9:25 am
Great video Bryan.
I am guessing you used an empty but primed cartridge? No bullet?
Suggestion, fill the empty case with styrofoam, seat and crimp a bullet in the cartridge, then repeat the test.
I have a few different tests in mind just for discussions. Wax bullets, some powder and wax bullets. I have some cases with a tad oversized flash holes I use with wax bullets etc.

Onec I get the small stuff out of the way, I will re-position the barrel much closer to the blast wall and start with real bullets/powder

This is not exactly anything new for me since I used this same set-up for pressure testing. :-)
User avatar
Sixgun
Posting leader...
Posts: 13077
Joined: Sun Sep 16, 2007 7:17 pm
Location: S.E. Pa....Where Trump is Supported and Common Sense Rules

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Sixgun »

Ok...I can't add nothing but I'm learning from your writings. Extremely interesting...not the same old "what crimp do you use"...If you need an old gun to blow up or something similar, let me know...I have most calibers.

My dad told me back in the thirties the neighborhood kids in the company owned coal mine housing used to position rifle cartridges into something and whack em with hammers and nails. Now you know why I am the way I am... :D
You've Seen Guns For Peace And Guns For War
But You've Never Seen Guns Like These Before!

Image
User avatar
Bryan Austin
Levergunner 2.0
Posts: 175
Joined: Sat Jan 08, 2011 6:05 pm
Contact:

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Bryan Austin »

Sixgun wrote:
Mon Oct 05, 2020 11:44 am
Ok...I can't add nothing but I'm learning from your writings. Extremely interesting...not the same old "what crimp do you use"...If you need an old gun to blow up or something similar, let me know...I have most calibers.

My dad told me back in the thirties the neighborhood kids in the company owned coal mine housing used to position rifle cartridges into something and whack em with hammers and nails. Now you know why I am the way I am... :D
lol, may need one!!!
User avatar
Bryan Austin
Levergunner 2.0
Posts: 175
Joined: Sat Jan 08, 2011 6:05 pm
Contact:

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Bryan Austin »

KWK wrote:
Mon Oct 05, 2020 9:54 am
You're a brave man, Bryan, or should I use a different adjective? :wink:

That firing pin and hammer have more inertia than the typical lever action does, apparently more than the impulse from the primer can bother. I'm looking forward to your future results; please post them here.
Very little tap is needed to activate the primer. I removed the firing pin so that I can reach the primer since I need to set the barrel further away but not too far. Just enough to see when the case head moves aft.
User avatar
Bryan Austin
Levergunner 2.0
Posts: 175
Joined: Sat Jan 08, 2011 6:05 pm
Contact:

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Bryan Austin »

video link
.
.
https://youtu.be/M9SE7x5eAqc


Working my up to higher pressures.
There is a reason fast draw guys use shotgun primers with wax bullets as well as enlarging the flash hole. Here you can see normal primers being used with wax bullet shoved all the way down on top of the primer. The primer is pushed out of the primer pocket from the primer blast trying to work it's way through that small flash hole into the case. The firing pin, or in this case the punch helps keep the primer from exiting the pocket. Other than the momentary use of the blunt object used to contact the punch, there is nothing holding the punch inside the firing pin housing.

When used in revolvers, the primer is pushed out against the blast shield but there is not enough pressure to force the case out in order to re-seat the primer back into the primer pocket. Shotgun primers and enlarged flash holes allows enough pressure to push the case out into the blast shield. The case does not expand into the chamber walls with such low pressures. All of the inertia comes from the primer blast. The resistance comes from the small primer hole and the wax bullet seated so far down into the case. The wax bullet makes a nice splatter against my basement wall ;-)
User avatar
KWK
Senior Levergunner
Posts: 1012
Joined: Fri Sep 07, 2007 10:31 am
Location: U.S.A.
Contact:

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by KWK »

KWK wrote:
Mon Oct 05, 2020 8:39 am
... still puzzle me... during the rapid pressure drop that occurs once the bullet is out, the pressure in the case will drop to the point cling stops and the case should blow rearward.
Thinking about it again, the drag of the primer on its pocket must be the explanation. The case mouth would be the last to let go of the walls, and once it does, the gas pressure would be transmitted to all sides of the brass, leaving no net force to push the case back. Also, the friction of the primer to it's pocket is reinforced by any remaining gas pressure.
User avatar
Bryan Austin
Levergunner 2.0
Posts: 175
Joined: Sat Jan 08, 2011 6:05 pm
Contact:

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Bryan Austin »

Well, I tried 4gr of Unique and a 220gr 43-214A bullet. Check out the results on the website.

https://sites.google.com/view/44winches ... t-pressure

Video here: https://www.youtube.com/watch?v=2Ex7DM2BG30


Unique4gr43214A.jpg
Case remained in chamber, primer came almost all the way out if it had not been for the punch used as a firing pin. Punch was not moved aft after hit with blunt object.

Unique4gr43214A1.jpg
Unique4gr43214A2.jpg
Target 16ft.

Unique4gr43214A3.jpg
Bullet penetrated 1 1/4" and lodges just inside 4x4 post

Unique4gr43214A4.jpg
You do not have the required permissions to view the files attached to this post.
User avatar
KWK
Senior Levergunner
Posts: 1012
Joined: Fri Sep 07, 2007 10:31 am
Location: U.S.A.
Contact:

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by KWK »

Nice work. I'm surprised by what appears to be blowby at the primer. I'd have thought it would seal pretty much instantly.
User avatar
Bryan Austin
Levergunner 2.0
Posts: 175
Joined: Sat Jan 08, 2011 6:05 pm
Contact:

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Bryan Austin »

KWK wrote:
Wed Oct 07, 2020 8:12 pm
Nice work. I'm surprised by what appears to be blowby at the primer. I'd have thought it would seal pretty much instantly.
The issue with the seal is that the case was set with such a large headspace for demonstrational purposes. The primer almost came all the way out but was slightly held in place by the "punch". The primer actually cocked a bit sideways completely loosing the seal.

My next tests, I will have to reset the barrel closer to the blast plate. I will also lock the blast plate down with a clamp. I am trying to leave enough of a gap so we can visually see with ease if the case moves aft.
User avatar
Sixgun
Posting leader...
Posts: 13077
Joined: Sun Sep 16, 2007 7:17 pm
Location: S.E. Pa....Where Trump is Supported and Common Sense Rules

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Sixgun »

Very interesting Bryan......so no thrust..yet......you got big ones!

Whatever you do don't experiment with 50 BMG primers like I did years ago....after drilling a hole in the side of the brass case to empty the powder...gotta use a sharp drill bit to get through before it heats up. :D l....I put the case in a vise and whacked it with a punch even though some oil in the case would have had the same result.......(I was in my twenties).....and the primer went off with the power of about 10 regular primers........the blast blew something up and made mince meat out of my forefinger.......

Yea, being Italian is a lot of fun sometimes....---6
You've Seen Guns For Peace And Guns For War
But You've Never Seen Guns Like These Before!

Image
User avatar
Bryan Austin
Levergunner 2.0
Posts: 175
Joined: Sat Jan 08, 2011 6:05 pm
Contact:

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Bryan Austin »

Sixgun wrote:
Thu Oct 08, 2020 12:41 pm
Very interesting Bryan......so no thrust..yet......you got big ones!

Whatever you do don't experiment with 50 BMG primers like I did years ago....after drilling a hole in the side of the brass case to empty the powder...gotta use a sharp drill bit to get through before it heats up. :D l....I put the case in a vise and whacked it with a punch even though some oil in the case would have had the same result.......(I was in my twenties).....and the primer went off with the power of about 10 regular primers........the blast blew something up and made mince meat out of my forefinger.......

Yea, being Italian is a lot of fun sometimes....---6
LOL, glad it all worked out!!

Oh yeah, expect a bit more caution as the powder charge gets larger.
User avatar
Sixgun
Posting leader...
Posts: 13077
Joined: Sun Sep 16, 2007 7:17 pm
Location: S.E. Pa....Where Trump is Supported and Common Sense Rules

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Sixgun »

One of the items I've always wanted to know is "what is the pressure level" when thrust becomes a meaningful force? I understand that there are many variables to be counted as in the most important is case design as in taper and quickness of the powder burn rate.....then comes thickness in brass and other outside variables such as oil or condition of the chamber........

.22 Jet is a prime example....I had one some years back and did all of what I was taold as per reloading manuals....oil free cases and chambers were paramount with the Jet. It was just too finicky for me so I moved it. Regular moderate loads were trouble free but I could have done that with a .22 mag.....

4198 will lock up the action in a 25-35 easily....it's the most accurate powder but it's hard to reach near max velocities without getting the lock up. Same with the 33 Winchester.....3031 will lock it up but 4064/4895 won't.

So......if your using 4 of unique my hypothesis is that about 8-10 grains will creat thrust...NO! don't do. Leave those things to people like me......you know, the guys who hand you their beer and exclaim, "watch this".... :D ----006
You've Seen Guns For Peace And Guns For War
But You've Never Seen Guns Like These Before!

Image
User avatar
Old Savage
Posting leader...
Posts: 13822
Joined: Mon Sep 03, 2007 3:43 pm
Location: Southern California

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Old Savage »

006, check out the 25-35 on Gunblast for AA 2460 results. I have that rifle but haven't found 2460.
In the High Desert of Southern Calif. ..."on the cutting edge of going back in time"...
User avatar
Bryan Austin
Levergunner 2.0
Posts: 175
Joined: Sat Jan 08, 2011 6:05 pm
Contact:

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Bryan Austin »

Sixgun wrote:
Thu Oct 08, 2020 1:53 pm
One of the items I've always wanted to know is "what is the pressure level" when thrust becomes a meaningful force? I understand that there are many variables to be counted as in the most important is case design as in taper and quickness of the powder burn rate.....then comes thickness in brass and other outside variables such as oil or condition of the chamber........

.22 Jet is a prime example....I had one some years back and did all of what I was taold as per reloading manuals....oil free cases and chambers were paramount with the Jet. It was just too finicky for me so I moved it. Regular moderate loads were trouble free but I could have done that with a .22 mag.....

4198 will lock up the action in a 25-35 easily....it's the most accurate powder but it's hard to reach near max velocities without getting the lock up. Same with the 33 Winchester.....3031 will lock it up but 4064/4895 won't.

So......if your using 4 of unique my hypothesis is that about 8-10 grains will creat thrust...NO! don't do. Leave those things to people like me......you know, the guys who hand you their beer and exclaim, "watch this".... :D ----006
LOL, too late, that was already my plan for Saturday. Saturday the wife will be at work, it will be raining so all my neighbors will be inside....so I should be able to kick off one or two rounds. I live by two major highways so I can blame it on a backfire! The smell of burn powder will be gone by the time the wife gets home but not before the cops show up ;-)
User avatar
Sixgun
Posting leader...
Posts: 13077
Joined: Sun Sep 16, 2007 7:17 pm
Location: S.E. Pa....Where Trump is Supported and Common Sense Rules

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Sixgun »

I hear ya Bryan....I married the farmers daughter so back in '72 there were gunshots around here all the time....
Everyone else stopped except me and a few others....I keep them used to it. I've had people tell me that when someone is visiting their house and they hear a gunshot, they just tell them.."ahhh that's a guy down the road, he's always shooting something." Whenever a new neighbor moves in I have to "break em in"....the state boys will show up telling me they "have to investigate", we laugh and tell jokes and then the cops go back and tell the new people, "relax, it's OK, he's a good ole boy."

We don't have any laws restricting shooting...just a law that says you have to have a backstop.......I always tell the boys, "shoot but use common sense, no one wants to hear an '06 going off on a Sunday afternoon but most people don't mind hearing Target velocity .22's or other subsonic cast bullet loads as long as the weather is bad and it's NOT a LOT of shooting.....this way there won't be an ordinance and don't make a reason for them."

Good thing you and I are not neighbors.....man! We'd have an underground shooting facility doing all sorts of devious experiments... :D ----6
You've Seen Guns For Peace And Guns For War
But You've Never Seen Guns Like These Before!

Image
User avatar
Bryan Austin
Levergunner 2.0
Posts: 175
Joined: Sat Jan 08, 2011 6:05 pm
Contact:

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Bryan Austin »

Sixgun wrote:
Thu Oct 08, 2020 3:05 pm
Good thing you and I are not neighbors.....man! We'd have an underground shooting facility doing all sorts of devious experiments... :D ----6
:lol:

Yeap!! Boy I do miss my land in Georgia. Use to shoot right out of the garage!!
User avatar
Bryan Austin
Levergunner 2.0
Posts: 175
Joined: Sat Jan 08, 2011 6:05 pm
Contact:

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Bryan Austin »

Stand-By to Stand-By....I have results!!!!!!

Just finished testing a nice cowboy load, results as follows....photos and videos later!!!

6.4gr Trailboss
Case thrust against "bolt", but very little. firing pin (punch) was kicked aft about 1.5", case moved aft out of chamber about 1/8" before hitting blast plate.

220gr bullet traveled 16 feet, entered one 1/2" plywood and passed through a 4 x 4, then hitting a nice steel plate ;-) (I ain't that stupid)

Primer nicely and fully reseated back into the case.

6.4gr of TB and a 200gr bullet only gave me 925 fps in my Marlin 1894CB so the 220gr might be a tad slower and maybe a tad more pressures but probably not much,

Pre-Tested pressures were only 7,224 psi. I call this rock bottom pressures before the case makes good contact with the bolt. There is no way in you know where that these pressure, no matter how repetitive will break or even stretch frames or toggles. There is no way an additional 5,000 psi will harm the toggles or stretch frames either. If folks are breaking parts, they are shooting much higher pressure loads and ignornat or lying about it.


I will edit this post but wanted to get this out there
User avatar
Bryan Austin
Levergunner 2.0
Posts: 175
Joined: Sat Jan 08, 2011 6:05 pm
Contact:

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Bryan Austin »

This test was performed using 6.4gr of Trailboss. I chose this load because it gave me the lowest pressure recordings of my handloads which were higher than Winchester Super-X hunting loads and Magtech Cowboy loads.

6.4gr, 220gr

43-214A lead bullet

7,224 psi @ only 925 fps...but we are focused on pressures, not velocities. (Winchester Supoer-X factory loads are 1,025 fps @ only 6,600 psi), I may test some of those loads as well.

Target 16 feet

Penetrated 1 ea, 1/2" plywood and a 4x4 post

Hit a 1" thick steel plate and came to rest on the concrete floor directly below the steel plate.

Video 1 - https://www.youtube.com/watch?v=ouubO57FG14
Video 2 - https://www.youtube.com/watch?v=g5qDc4dYj60
Trailboss6.4gr2.jpg
Trailboss6.4gr3.jpg
Trailboss6.4gr4.jpg
Trailboss6.4gr5.jpg
You do not have the required permissions to view the files attached to this post.
User avatar
Sixgun
Posting leader...
Posts: 13077
Joined: Sun Sep 16, 2007 7:17 pm
Location: S.E. Pa....Where Trump is Supported and Common Sense Rules

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Sixgun »

Bryan,
Thanks a lot for taking the time and energy to post this......I call these posts "a post of substance" and not a post where the title line is "What Color Socks Do You Wear When Buying A Loaf Of Bread?"

I could be wrong but is the end of your punch rounded out and polished like a firing pin? I do know from experience a firing pin that is out of round or has a burr on it can cause erratic ignition or possibly blow by.

6.4 grains of Trail Boss for close to a thousand FPS. I'm not familiar with that powder but it appears to be about like 231 in burn rate.

Your tests are bring back memories. I had a Remington rolling block in 45-70 that had around .025 of excessive headspace....it was a screw in barrel from numrich and that's just how it screwed in....very visible air space between the case head and block. With my loads of 11-13 gr. of Unique the primer would back near half way out.....shot thousands of rounds with no problems.....I sold the rifle and that guy came back to me complaining about cases splitting in half near the head....he used factory 300 gr ammo that was advertised as 1800...I'm guessing 18K pressure. Another below...

I had a Marlin model 27 pump in 25-20 that worked like the old Lightning as in it didn't lock up on firing....I used to shoot velocities in the 18K range and on firing the action would almost work itself with the pump handle coming half way back....

Ahhh....got some stuff to do...until later.....006
You've Seen Guns For Peace And Guns For War
But You've Never Seen Guns Like These Before!

Image
User avatar
KWK
Senior Levergunner
Posts: 1012
Joined: Fri Sep 07, 2007 10:31 am
Location: U.S.A.
Contact:

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by KWK »

With the greater head space currently in your set up, the pressurized primer will not apply as much drag to help resist the case coming backward. Just to see if there is any effect, you might move the blast plate forward and try to replicate John Kort's test.

Excellent work, Bryan, thank you. I look forward to your next test.

Earlier today I sent a note to Varmint Al with some questions on his primer thrust calculations. Sadly, he no long has access to the engineering software he used to run his analysis. :cry:
User avatar
Bryan Austin
Levergunner 2.0
Posts: 175
Joined: Sat Jan 08, 2011 6:05 pm
Contact:

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Bryan Austin »

Sixgun wrote:
Thu Oct 08, 2020 8:12 pm
Bryan,
Thanks a lot for taking the time and energy to post this......I call these posts "a post of substance" and not a post where the title line is "What Color Socks Do You Wear When Buying A Loaf Of Bread?"

I could be wrong but is the end of your punch rounded out and polished like a firing pin? I do know from experience a firing pin that is out of round or has a burr on it can cause erratic ignition or possibly blow by.

6.4 grains of Trail Boss for close to a thousand FPS. I'm not familiar with that powder but it appears to be about like 231 in burn rate.

Your tests are bring back memories. I had a Remington rolling block in 45-70 that had around .025 of excessive headspace....it was a screw in barrel from numrich and that's just how it screwed in....very visible air space between the case head and block. With my loads of 11-13 gr. of Unique the primer would back near half way out.....shot thousands of rounds with no problems.....I sold the rifle and that guy came back to me complaining about cases splitting in half near the head....he used factory 300 gr ammo that was advertised as 1800...I'm guessing 18K pressure. Another below...

I had a Marlin model 27 pump in 25-20 that worked like the old Lightning as in it didn't lock up on firing....I used to shoot velocities in the 18K range and on firing the action would almost work itself with the pump handle coming half way back....

Ahhh....got some stuff to do...until later.....006
The punch is a bit crude but I did "round-off" the end. It is also a bit larger than a firing pin which could alter, or in this case....be one of many factors that can alter results!

Trailboss is a bulky, fast burning pistol powder and (for others reading this) should never ever be confused with slower burning rifle powders like 2400, IMR-4227, Reloder 7, H4198, IMR-4198 etc.

Yeap, I am now beginning to think that guys are shooting hot loads in these brass frames and early toggles and not coming forth with the truth. As I mentioned, they are ignorant as to what they are using or they are telling fibs!!!!
User avatar
Sixgun
Posting leader...
Posts: 13077
Joined: Sun Sep 16, 2007 7:17 pm
Location: S.E. Pa....Where Trump is Supported and Common Sense Rules

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Sixgun »

Guys who shoot hotter than safe loads in their guns will admit that about the same as they will admit they drive drunk. While I'm not a ballistician nor a metallurgist I can say with certainty that many of the old leverguns that are out there that have excessive headspace have it NOT because of lots of use but by excessive pressure setting everything back. 1895 Winchesters in 30-06 are an example of both of those abuses where 1873's and 1892's are mostly due to excessive pressure.

If a gun is kept clean and pressures are what is designed for the gun it should shoot many thousands of times with no issues....I have proved that with many old guns, even a Colt Lightning made in 1888 that has eaten (got to look at my log) probably 4 thousand rds.

You can pick up a firing pin for an AR for $5 or $10. Centrally locate it in a jig and you will narrow down the variables...--6
You've Seen Guns For Peace And Guns For War
But You've Never Seen Guns Like These Before!

Image
User avatar
Bryan Austin
Levergunner 2.0
Posts: 175
Joined: Sat Jan 08, 2011 6:05 pm
Contact:

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Bryan Austin »

I tested a few more shots yesterday evening with the same results. What I can not do is test at what pressures the cases expand and to what pressures the bolt is subject to. If the case does not expand and the case thrusts back into the bolt, one would think the amount of pressure created in the chamber is what the bolt will be subject to. Either way, I have no way of testing this right now. If the case expands and is held by friction at X amout of pressure, what is the presser when the case is released? When released there will be enough pressure to thrust against the bolt.

Anyhow, I think we concluded that John was correct in saying that there is [little to] no thrust on the bolt at low pressures. I think the pressures are certainly lower than 7,000psi and maybe even 6,000 psi depending on chamber and case conditions such as oil, roughness/smoothness etc. I also think the bolt (Winchester 73' as a reminder) is not subject to as much thrust as many think with 44-40 loads, even factory loads. I also think this creates more questions than it answers but it still doesn't answer the question how much thrust will the bolt endure and survive longevity.

Then there is always the Winchester 73' replicas chambered in 44 Magnum that folks claim the parts are the same, made from the same material.
User avatar
KWK
Senior Levergunner
Posts: 1012
Joined: Fri Sep 07, 2007 10:31 am
Location: U.S.A.
Contact:

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by KWK »

In all your tests, the primer has reached the blast plate. Clearly, then, there is thrust on the bolt at these pressures.

I think that at the minimum, the force off the primer will be peak pressure times the area over the ID of the primer cup. I suspect the area at the OD of the primer cup is closer to correct, but Varmint Al's simulation indicates ID. However, Al can't look back at his simulation inputs and results, so the question is up in the air, at least as far as calculation goes.

Minimum pressure to seal at the case mouth is in the vicinity of 2000 psi, and any useful load will exceed that.
User avatar
Bryan Austin
Levergunner 2.0
Posts: 175
Joined: Sat Jan 08, 2011 6:05 pm
Contact:

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Bryan Austin »

KWK wrote:
Sat Oct 10, 2020 10:53 pm
In all your tests, the primer has reached the blast plate. Clearly, then, there is thrust on the bolt at these pressures.

I think that at the minimum, the force off the primer will be peak pressure times the area over the ID of the primer cup. I suspect the area at the OD of the primer cup is closer to correct, but Varmint Al's simulation indicates ID. However, Al can't look back at his simulation inputs and results, so the question is up in the air, at least as far as calculation goes.

Minimum pressure to seal at the case mouth is in the vicinity of 2000 psi, and any useful load will exceed that.
KWK, I isread your reply and I am editing.
Actually, not the first one. The primer did not reach the thrust plate. As I explained, the thrust plate "floats" so when fired, it "bounced" into the primer. The firing pin was not pushed back and the primer nearly came out and was slightly turned turned. The blast plate was clamped down after that. Other tests yielded the same results. I have to disagree with the 2,000 psi case mouth seal but I will see what I can find. It is well known that if the 44-40 is loaded too light, the case will not thrust back into the blast shield and re-seat the primer, causing the primer interfere with the blast plate and lock up the cylinder.
Unique4gr43214A.jpg
You do not have the required permissions to view the files attached to this post.
User avatar
Bryan Austin
Levergunner 2.0
Posts: 175
Joined: Sat Jan 08, 2011 6:05 pm
Contact:

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Bryan Austin »

KWK,

Just for you I just made this video. Again it is 4gr of Unique with a 220gr bullet. The video, in your defense, this time shows slight aft thrust BUT look at the rest of the story.

Before testing I gave the blast plate a fresh light coat of flat black paint. With the paint still wet, but the paint "flashing over" only by two minutes, I fired this shot. The photos show that the case head barely tapped the top side of the plate as well as the primer around the hole and the primer did not seat flush. There primer extrudes .006"...my 73" has a .007" headspace, thus, little to no thrust on the bolt face. I did not snap a photo but the case mouth did not seal, or seal fast enough because there is black soot on the bottom of the exterior of the case neck. If you look closely in the video, you will actually see a gap between the case head and the blast plate, and it is obvious the primer it touching.

I think I will go with my tests over theory for a 50,000 psi cartridge engineered animation.
Unique4grsecondary.jpg
Unique4grsecondary2.jpg
VIDEO - https://www.youtube.com/watch?v=JXw3eTNa-MA

However, it would only be fair to shoot ten and average the results since pressure ES can very. I didn't shoot ten but I am happy with the results.

I will try 5gr and then 6gr, but again, unless groups of at least ten shots are averaged, I don't expect much in increased pressures, but I do expect a little more evidence of more force on the plate.
You do not have the required permissions to view the files attached to this post.
User avatar
Bryan Austin
Levergunner 2.0
Posts: 175
Joined: Sat Jan 08, 2011 6:05 pm
Contact:

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Bryan Austin »

5gr of Unique did not do much more.
Unique5grSecondary1.jpg
Unique5grSecondary.jpg
VIDEO - https://www.youtube.com/watch?v=B4ENVK5q8j0

The case head really did not contact the blast plate, only the primer.
You do not have the required permissions to view the files attached to this post.
User avatar
Bryan Austin
Levergunner 2.0
Posts: 175
Joined: Sat Jan 08, 2011 6:05 pm
Contact:

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Bryan Austin »

6gr Unique.

Rather than keep posting more of the same, here is the blast plate with fresh paint showing the contact. The plate is slightly angled when clamped in place (typically I let it float) so the top part of the case head hits first. This time there is a bit more evidence of the top part of the case head contacting the blast plate. 6gr of Unique with a 220gr lead bullet should still in the 6,500 psi range. Two ten shot groups with 8gr of Unique with only a 200gr bullet gave me an avg of 8,800 psi

According to Lyman's 49th, 6.3gr is minimum with a 427098 and 7.9gr max. Many CAS shooters don't even use 6gr, I did ask for a poll vote here. https://forums.sassnet.com/index.php?/t ... th-unique/
Unique6grSecondary.jpg
You do not have the required permissions to view the files attached to this post.
User avatar
Bryan Austin
Levergunner 2.0
Posts: 175
Joined: Sat Jan 08, 2011 6:05 pm
Contact:

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Bryan Austin »

This will be my last post.

This is 8.6gr of Unique with a 220gr 43-214A. Bullet penetrated 5" of pine board at 16 feet. 1 piece of 1" thick plywood followed by a 4x4 post. Bullet struck second 4x4 board but remained in first one. I added this information because 8.6gr is my normal revolver load.

Better contact with the blast plate, but slight it was. Flatter hit. The "scrape marks" on the fresh paint is where the plate rubbed the case head as I removed the plate. Primmer was re-seated into the primer hole. The punch acting as the firing pin remained in place, no aft movement.

I Pressuretraced 8.5gr with a .430" Speer SJHP and recorded 1,164 fps @ 11,363 psi. I estimate 11,000 psi with the 8.6gr 220gr 43-214A load
Unique8.6grSecondary1.jpg
.
You do not have the required permissions to view the files attached to this post.
User avatar
KWK
Senior Levergunner
Posts: 1012
Joined: Fri Sep 07, 2007 10:31 am
Location: U.S.A.
Contact:

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by KWK »

I have to disagree with the 2,000 psi case mouth seal...
I'll explain my 2000 psi estimate of case sealing in this post, then this evening I'll go review all your posts of the last few days and see what I misunderstood in those.

If one sections a .44 WCF case longitudinally, then the case neck makes for two thin strips of brass about .01" across tasked with holding back internal gas pressure acting on the case I.D. of about .42" across. If the brass is work hardened some (reloaded), it might be rated as quarter hard, in which case it will begin to take on a permanent set at about 40,000 psi (and it does take on a permanent set, else we wouldn't have to resize the neck). So, 40 ksi over .02 of brass can hold back gas pressure of 40 * (.02/.42) = about 2000 psi. If the brass was freshly annealed, it would take on a set at less than 20 ksi in the brass, so the neck would begin to blow out to the chamber around 1000 psi.

This "hoop stress" calculation is pretty basic, but your PressureTrace is surely doing the same calculation when it tries to figure out how much pressure the case is taking before it begins to strain the steel where the gauge is attached. That's why they ask you for the brass thickness under the strain gauge (or at least I recall they did in their demo software I tried many years ago).

Being lazy, I plucked the brass properties from Varmint Al's site, down near the bottom of the page. If you want to see more of the calculations PressureTrace does, this archived page is from the former site of a fellow who sold a strain gauge unit which preceded PressureTrace to market.

Soot on the neck implies gas blowing by, but that can come as the gas pressure is ramping up or ramping down, and of course will also depend on how sooty is the burn as well as how slowly it ramps down (and I'm sure other factors I'm missing at the moment).

Thanks for all the pictures and descriptions.
Last edited by KWK on Sun Oct 11, 2020 11:12 am, edited 1 time in total.
User avatar
Sixgun
Posting leader...
Posts: 13077
Joined: Sun Sep 16, 2007 7:17 pm
Location: S.E. Pa....Where Trump is Supported and Common Sense Rules

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Sixgun »

Thank you Bryan....I'm reading......your experiments showed me you reached about what is a maximum load for an original 1873.....The ballisticians who write loading manuals must know the point where bolt thrust actually starts....explains why I was getting case separations with 10 of unique in an original 1873...yes, that was a long time ago..1975 to be exact.....

There! I feel better, I told the truth! :D ----6
You've Seen Guns For Peace And Guns For War
But You've Never Seen Guns Like These Before!

Image
User avatar
Bryan Austin
Levergunner 2.0
Posts: 175
Joined: Sat Jan 08, 2011 6:05 pm
Contact:

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Bryan Austin »

Sixgun wrote:
Sun Oct 11, 2020 11:05 am
Thank you Bryan....I'm reading......your experiments showed me you reached about what is a maximum load for an original 1873.....The ballisticians who write loading manuals must know the point where bolt thrust actually starts....explains why I was getting case separations with 10 of unique in an original 1873...yes, that was a long time ago..1975 to be exact.....

There! I feel better, I told the truth! :D ----6
Thanks Sixgun....
Maybe,

Black powder loads I tested in original pre-1884 cases yielded 14,000 psi while the pressures decreased over the years as case designs improved, 12,000 psi, 11,000 psi 10,000 psi and then finally 8,953 psi with Starline brass. This could give us a hint as to what might be happening. Anyhow, I think old original 73's should be left alone but new 73's are offered in 44 Magnum using the same parts for other calibers. The only difference in parts is what is needed to accommodate a specific caliber. I never did think to as Larry if he tested 44 Mangum factory loads but I doubt they ere close to SAAMI max loads of 36,000 psi. His Reloder 7, 25gr loads, ranged from 17,000 psi to 24,000 psi. Factory 240gr 44 Magnum loads would certainty be safe in the 44 Magnum 73's.

To conclude, I will continue to shoot my 13,000 psi loads and maintain frequent inspections and let ya'll know if I break something.
User avatar
KWK
Senior Levergunner
Posts: 1012
Joined: Fri Sep 07, 2007 10:31 am
Location: U.S.A.
Contact:

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by KWK »

Bryan Austin wrote:
Sun Oct 11, 2020 12:06 pm
... new 73's are offered in 44 Magnum using the same parts for other calibers.. Factory 240gr 44 Magnum loads would certainty be safe in the 44 Magnum 73's.
I've exchanged messages with guys who own .44 Mag '73's and they seem happy with them. I asked one of the importers what they'd seen over they years, and reading between the lines of their reply I took it they do wear faster.

Why do you feel the factory .44 Mag loads would be safe in a modern '73 -- beyond the fact they aren't flying apart?
User avatar
Sixgun
Posting leader...
Posts: 13077
Joined: Sun Sep 16, 2007 7:17 pm
Location: S.E. Pa....Where Trump is Supported and Common Sense Rules

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Sixgun »

Thanks Bryan for giving away knowledge that was gained from hours of dedicated work....I find it interesting....the firearm manufacturers know these things as they have the brightest minds and equipment for the testing but they keep us like a mushroom, "in the dark and feed us HRC."

Some of what I have learned here with your tests brings back memories from the past that I had long forgotten about....an 1892 Winchester in perfect condition in 32-20 loaded with more Unique than I should have used broke the ejector after three rounds.....it could have been a coincidence but it must have been bolt thrust...the 1892 uses a split bolt face like the 1886 does....not sure if I used the correct terminology but the ejector closes even with the rest of the bolt face upon closing on a loaded round.----6
You've Seen Guns For Peace And Guns For War
But You've Never Seen Guns Like These Before!

Image
User avatar
Bryan Austin
Levergunner 2.0
Posts: 175
Joined: Sat Jan 08, 2011 6:05 pm
Contact:

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Bryan Austin »

KWK wrote:
Sun Oct 11, 2020 12:24 pm
Bryan Austin wrote:
Sun Oct 11, 2020 12:06 pm
... new 73's are offered in 44 Magnum using the same parts for other calibers.. Factory 240gr 44 Magnum loads would certainty be safe in the 44 Magnum 73's.
I've exchanged messages with guys who own .44 Mag '73's and they seem happy with them. I asked one of the importers what they'd seen over they years, and reading between the lines of their reply I took it they do wear faster.

Why do you feel the factory .44 Mag loads would be safe in a modern '73 -- beyond the fact they aren't flying apart?
Because the factory sells them to perform as such? Like I said, the parts, i.e. pins, are the same for all Uberti 73's whether 357, 44-40, 45 Colt for 44 Magnum. Why would the bolt of a 44 Mag 73' not withstand the same pressures as the 45 Colt or 44-40? That is for those that think repetitive 15,000 psi 44-40 loads are bad for the 73's bolt/toggles. Of course things wear, that's why we inspect things.

Oh just out of curiosity...can you convert hammer pull tension from tension lbs to psi? What would it take in chamber psi to recoil a bolt the same distance as a 4lb hammer pull (trigger scale)? If the answer is 4, that shows just how dumb I really am.
User avatar
Bryan Austin
Levergunner 2.0
Posts: 175
Joined: Sat Jan 08, 2011 6:05 pm
Contact:

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Bryan Austin »

Sixgun wrote:
Sun Oct 11, 2020 12:32 pm
Thanks Bryan for giving away knowledge that was gained from hours of dedicated work....I find it interesting....the firearm manufacturers know these things as they have the brightest minds and equipment for the testing but they keep us like a mushroom, "in the dark and feed us HRC."

Some of what I have learned here with your tests brings back memories from the past that I had long forgotten about....an 1892 Winchester in perfect condition in 32-20 loaded with more Unique than I should have used broke the ejector after three rounds.....it could have been a coincidence but it must have been bolt thrust...the 1892 uses a split bolt face like the 1886 does....not sure if I used the correct terminology but the ejector closes even with the rest of the bolt face upon closing on a loaded round.----6
Yeap, things that make us go .....Hmmmmmmm!
User avatar
KWK
Senior Levergunner
Posts: 1012
Joined: Fri Sep 07, 2007 10:31 am
Location: U.S.A.
Contact:

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by KWK »

Bryan, I looked at your photos from this morning of the plate with 4, 5, and 6 gr of charge. It looks as if the primer was on the plate in all 3 tries. If so, I can't conclude bolt thrust is zero, unless there is something about the plate or it's motion that I'm missing.

There are two gas pistons acting on the breech/bolt. One is the case, and one is the primer. Both John's and your tests have shown that at some pressures, the case's contribution is nil. This surprised me, so I did some basic calculations to understand why. However, so long as the primer contacts the breech, there exists the possibility of thrust. I can only estimate it by calculation. Without a test, calculations can lead one astray. Without calculations, the wrong conclusions can be drawn from a test. Engineers generally aren't content unless the two ways agree.

You asked a question about a 4 lb hammer pull. I'm sorry but must admit I don't understand the question.

Karl
User avatar
Bryan Austin
Levergunner 2.0
Posts: 175
Joined: Sat Jan 08, 2011 6:05 pm
Contact:

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by Bryan Austin »

KWK wrote:
Sun Oct 11, 2020 8:52 pm
Bryan, I looked at your photos from this morning of the plate with 4, 5, and 6 gr of charge. It looks as if the primer was on the plate in all 3 tries. If so, I can't conclude bolt thrust is zero, unless there is something about the plate or it's motion that I'm missing.

There are two gas pistons acting on the breech/bolt. One is the case, and one is the primer. Both John's and your tests have shown that at some pressures, the case's contribution is nil. This surprised me, so I did some basic calculations to understand why. However, so long as the primer contacts the breech, there exists the possibility of thrust. I can only estimate it by calculation. Without a test, calculations can lead one astray. Without calculations, the wrong conclusions can be drawn from a test. Engineers generally aren't content unless the two ways agree.

You asked a question about a 4 lb hammer pull. I'm sorry but must admit I don't understand the question.

Karl
I must agree that when the primer hits the bolt, even though the case does/may not, there is at lease some thrust on the bolt. Certainly this would mean the thrust would be light and leads me to the question you didn't understand. I really didn't expect folks to understand my questions. My question asking skills suck!!

Today I took my Uberti Winchester 73' and removed the toggles. I loaded 4gr of Unique and a wax bullet (Fast Draw wax bullets) and let it rock. (Please folks, do not try this with lead bullets) The only thing there to stop the aft movement of the bolt was nothing more than the hammer spring. The bolt thrusted aft approximately 3/4". I used a string and a trigger scale and pulled 4lbs to achieve the same position. (see photo). The primmer re-seated .002" shy of flush with the primer pocket. If bolt headspace is .007" then the thrust was enough to push primer.005" back into the primer pocket...I think! Still not a lot of thrust on the bolt face I guess but enough to thrust the bolt aft 3/4" against the tension of the hammer spring by 4 lbs. Can you interpret? LOL!
Unique4grWAX4lbshammertension.jpg
VIDEO - https://www.youtube.com/watch?v=hsmj2mA4H4Y
You do not have the required permissions to view the files attached to this post.
User avatar
AJMD429
Posting leader...
Posts: 26952
Joined: Sun Sep 09, 2007 10:03 am
Location: Hoosierland
Contact:

Re: Bolt Thrust Experiment #3 .22 LR & .44-40

Post by AJMD429 »

My intuition says the big thing is the inertia of the bolt and the brevity of the force.

Not being an engineer I can’t quantify the results or prove my theory, however.... :oops:

Still, think about a really heavy door like at the end of the hallway when I was running down the hall in high school and a teacher yelled to stop; as a red-blooded senior I just ran faster, but when I hit the panic-bar and door that outweighed me, it barely moved, and my kinetic energy deflected UP...so my forehead hit the hydraulic door-closer... :shock: . A few yards outside and blood streamed down my forehead... :lol: :oops:

Now, had I applied LESS force to the door, but over a more sustained time, it would have opened far more easily and completely...but I wouldn’t have gotten the martyrdom and sympathy that afternoon from the chick I had a crush on who was in my trigonometry class... :D
Doctors for Sensible Gun Laws
"first do no harm" - gun control LAWS lead to far more deaths than 'easy access' ever could.


Want REAL change? . . . . . "Boortz/Nugent in 2012 . . . ! "
Post Reply