Pressure wave theory ringing chambers? Anybody believe it?

[Aggiecubpilot]

Hello everybody,

As I have mentioned recently, along with many many others in the past, Unique and cast bullets have been particularly good to me in my 45-70. However I continue to read voraciously all that I can on this cartridge and loads for it. Lately I have stumbled upon commentary, I believe on another site, which admonish such a load even though it is well published, seemingly time tested data. We all have read thread after thread which recommend this powder and sundry cast bullet mould/weight combinations.

I realize that there is some risk in choosing virtually any loading, regardless of how safe others say it is, and just because it is safe in another's rifle doesn't mean it will be safe in mine. However I am interested in knowing if there is evidence to suggest that there may anything unsafe about such a load. I am curious why 2400, for example, is frequently debated in its use in the 45-70, while Unique is a crowd favorite. I also wonder why so many of the quicker burning powders have been dropped from the recent published data. Perhaps all we can do is speculate, blame lawyers and the like, but I know many of you have tested, studied and experimented far more than I have the means to at the moment, and I am interested in your findings.

While I have referred to 45-70 above, I am also interested in what the shooters of other similar cartridges have discovered.

I hope this is an interesting and enlightening discussion and I thank everybody for your thoughts!

[Cliff]

What I have heard and read concerning the ringing of chamber with light loads of fast powders comes from someone who will attempt to use a case filler leaving air space between the powder and the base of the bullet. Same effect as trying to fire a loaded cartridge w/bulllet to dislodge a stuck bullet in the barrel. Fire a cartridge case without a filler or bullet and the stuck bullet can usually punch the stuck bullet out of the barrel without damage. Leave a wad or bullet in the cartridge case you wind up with a ringed or bulged barrel, at the point the base of the stuck bullet was. Shotguns have thin barrels and usually can fail in this attempt. If you can find a copy read "Hatcher's Note Book" on his experience at Springfield Arsenal. Another one is a light load of improper powder. Most Ball powders don't like reduced loadings and the manufactures of the same advise against reduced loads with these powders. There are a lot theories on what can cause ringing or damage from reduced loads, most cannot be reduplicated in a lab. Stick to the published manuals loading data and you are usually good to go. Also contact the company making the powder for their suggestions. Be safe. Use proven data. That is my take.

[w30wcf]

For many years, "Sharpshooter" was used in factory loaded 45-70 cartridges. It was a dense powder with a burning rate similar to 2400. 24 grs. was the typical factory loading under a 405 gr bullet so there was plenty of airspace in the case.

Ditto to what Cliff said.

Back in the 1970's - 1980's, I shot about 1,000 rounds of 45-70 handloads with 15 grs of 700X and a 300 gr jacketed bullet with nary an issue.

w30wcf

[Charles]

I believe that"some rifles" in "some calibers" have suffered ringed chambers/barrels do to the use of "some fillers". Past those facts, there are just theories to explain it, and these theories at times are contradictory.

[earlmck]

I'm not buying any "pressure wave" theory. I think it is much more likely caused when a bullet is lodged in the barrel and an second round is fired behind without realizing the first bullet is lodged.

I think about 2 times in my life I have had a primer go off without igniting the powder. The only sensation I got at the time (I don't shoot without good ear protection any more since loosing a bunch of hearing as a kid...) was "misfire". Fortunately I am real nervous about "misfire" so stopped, waited, examined and found a bullet lodged in the barrel and a bunch of unburned powder making a mess of the action.

But I can well imagine that if I had been doing something like CASS or some rapid-fire competition I'd have pulled the trigger again without registering the danger and would have had something bad happen.

And Cliff's thoughts on the "filler-with-air-space" is interesting, though I'd have to see that happen to believe it, as I remember the times I just crammed a little wad of Kapok down to hold the powder back against the primer without paying much attention to unused space. No, I never had anything bad happen, but never got enough improvement in accuracy to justify the bother, so that is not a practice I did a whole bunch of.

[Pisgah]

"Pressure wave" sounds good, but IMO what is generally responsible is either A) overloads (a common problem with fast, low-volume powders in big cases, but user error and not a powder problem), and B) fillers. Fillers sound good, seem reasonable -- but they can have profound, unanticipated effects. I won't use 'em unless I see them in published, tested data -- and then only exactly as precribed.

[marlinman93]

Bullets lodged in the barrel will not cause chamber ringing, it will either bulge the barrel, or blow the barrel. Not having any effect on the chamber.
I have seen guns that showed visable signs of chamber ringing when a cast was made. In each one it was very hard to get the chamber casting out of the gun due to the ringed chamber. Both guns also had been fired with light smokeless loads using poly filler.
I've used Unique for years in my guns and never ringed a chamber, but I don't use fillers. Unique is not position sensitive, and burns fully regardless, so no filler is required.

[AJMD429]

I think about 2 times in my life I have had a primer go off without igniting the powder. The only sensation I got at the time (I don't shoot without good ear protection any more since loosing a bunch of hearing as a kid...) was "misfire". Fortunately I am real nervous about "misfire" so stopped, waited, examined and found a bullet lodged in the barrel and a bunch of unburned powder making a mess of the action.

But I can well imagine that if I had been doing something like CASS or some rapid-fire competition I'd have pulled the trigger again without registering the danger and would have had something bad happen.

I've never had an issue with a semiauto other than a .22 LR NOT making a bullet exit the barrel, but that is one reason I PREFER NON-SEMI-AUTO firearms for the bulk of my shooting; if a round malfunctions in a semiauto (many of which are bottle-neck, high-pressure rounds) and leaves a stuck bullet, I'm thinking your next trigger-pull will produce grenade-like results... Thankfully, most of the higher-powered semiautos out there are 'gas' operated, and if the bullet hasn't made it to the gas-port, there won't be another round loaded. I'm thinking it is very unlikely to make it past the gas port but not out the barrel.

I've used Unique for years in my guns and never ringed a chamber, but I don't use fillers. Unique is not position sensitive, and burns fully regardless, so no filler is required.

I've always wondered if there is a 'chart' somewhere showing which powders ARE 'position sensitive', and which ones tend not to be; I've read anectodal reports of folks doing chrony work with muzzle tipped 'up' or 'down' prior to firing, and there were sometimes differences of a couple hundred feet per second!

Anyone know of such a 'chart'...?

Just thinking about 'what could go wrong' with 'fillers', it seems like the most consistent result would be with either something mixed throughout the powder (but it would have to be exactly the same density and so on so as to not 'settle out' with jostling the cartridge), OR something assuredly packed on TOP of the powder which was 'solid' enough not to jostle out of place, akin to a polyethylene or fiber shotgun-wad. Of course if the case it tapered, the latter method becomes problematic and whatever is used has to be deformable enough to exit easily and uniformly. As far as the 'mixed in' filler, I'd think that could affect the burn/propagation rate enough that I would just not be comfortable doing so. So - I'm in the "no fillers for me" crowd, even though I'm sure some 'recipes' have been worked out that time has shown to be safe.

P.S. check this out, talking about 'fillers' - http://www.levergunscommunity.com/viewt ... =1&t=37785

I hope this is an interesting and enlightening discussion and I thank everybody for your thoughts!

THANKS for posting the interesting topic...