.30-30 Ackley Improved questions...

[nralover]

I believe I have posted this before, so let me apologize in advance. I can't seem to recall any replies, so here we go again:

I was thinking of rechambering a 336 to .30-30 AI, and I am curious about real world velocity/energy from a 20 inch barrel. As we all know, factory ammunition does not come close to meeting advertised velocities in a carbine. Most companies show their 150 grain offerings to be in the neighborhood of 2400 fps, when in actuality the 20 inch tubes are getting closer to 2250fps or so. If I were to rechamber, will I be able to safely get 2500 fps without going crazy on pressure, or is this a pipe dream?

[pdawg.shooter]

If you increase case capacity by 10% you can increase velocity by about 2 1/2% at the same pressure.

[nralover]

So 50-60 fps? Is that correct? Why would anyone even bother?

[pdawg.shooter]

Well, your cases will last longer. Plus it looks kind of neat!

[handirifle]

The key to the Ackley, is the statement, "at the same pressures". The 30-30, in factory loadings is loadedwell below what the Marlin can handle. If one has the means to measure actual pressures I believe the 2500 isn't out of line. Kinda along the same lines as Paco's article on the 375 BB Win. The factory ammo was loaded down to be able to be sold and used in the Marlins at 50,000 psi, but the Win 94 BB was designed to handle the 52,000 CUP that the 307, 356 and 375 were originally designed for. Most have averages the 52,000 CUP at 60,000 psi. The end result was water'd down performance to sell more ammo.

The SAAMI specs for the 30-30 are 42,000 psi and the Marlin is safely capable of 50,000. Taks the 45-70 as well. The SAAMI specs call for 28,000 psi, but all load manuals will push that to over 40,000 psi in the Marlin and higher in other rifles like the Ruger #1. But you do so at your own risk.

Keep in mind, different powders burn differently. Hornady get extra velocity fron the LE ammo by the type of powder used as well. A longer pressure curve will produce more velocity at even the same pressures. It has a longer "push" against the bullet. I have gotten more velocity for certain calibers with slower burning powders than with faster ones, simply due to powder performance.

What blows up rifles, isn't just pressure, it mainly the pressure "spike". One can achieve 60,000 psi in a barrel much safer if it's built up slowly, say within the first 10-12 inches of barrel, than if it hits the 60,000 in the first 8-10.

A comparison of recoil energy numbers can be a good comparison. The 45-70 loads, for example, although often showing higher numbers than other calibers, feel more like a "push" than a hard kick. Take the same numbers from a sharp shouldered magnum and it will much sharper and more painful. It's not the amount of energy, but how it's delivered. The same holds true at the receiving end. The 45-70 kills much more effectively then it's "numbers" would indicate.

Please take this info with the advice to proceed at your own risk, preferably with pressure equipment attached.

[TedH]

The Ackley cartridges are not intended to run at the same pressures as the parent case. Less body taper means less case head thrust. For what it's worth, I get 2500 fps from a Marlin with a 18.5" barrel without any excess pressure signs. That's with three grains more powder than the standard 30-30 max. load.

[nralover]

The Ackley cartridges are not intended to run at the same pressures as the parent case. Less body taper means less case head thrust. For what it's worth, I get 2500 fps from a Marlin with a 18.5" barrel without any excess pressure signs. That's with three grains more powder than the standard 30-30 max. load.

Ahh- now I see. I would never modify a rifle to get a 50 fps gain, but if I can safely get 250 fps, then it justifies the expense. I consider the .30WCF with FN bullets to be fully up to the task for deer size game out to 200 yards. As a matter of fact, I killed a nice doe at 190 last year with a 150 grain PMC hollow point. That kind of an increase in velocity and energy would be welcomed at those longer ranges...

[O.S.O.K.]

You will get 2500 fps from your 20" carbine with 150 grain bullets. I get close to 2587 fps with my 26" rifle with 39.5 grains of W748 under a 150 Gr. Speer. 40 Grains will give you 2500. Reloader 15 is supposed to give a little more at the same pressure - longer burn time I guess.

I intend to rechamber a Marlin myself - my 26" rifle is a Win 94. I'd like a Marlin chambered in 30-30 AI too. Maybe with a scope.

When do you intend to do the rechamber? Do you have a reamer yet? If not, perhaps I could bump up my Marlin purchase and then sell my reamer to you - it works great and I won't need it again after this second job. It's very nice as you simply ream until it stops - can't go too far as it has a step where the rim is to stop forward travel. I'd sell it for $50 shipped. But I need to get the rifle first...

[Don McDowell]

I believe I have posted this before, so let me apologize in advance. I can't seem to recall any replies, so here we go again:

I was thinking of rechambering a 336 to .30-30 AI, and I am curious about real world velocity/energy from a 20 inch barrel. As we all know, factory ammunition does not come close to meeting advertised velocities in a carbine. Most companies show their 150 grain offerings to be in the neighborhood of 2400 fps, when in actuality the 20 inch tubes are getting closer to 2250fps or so. If I were to rechamber, will I be able to safely get 2500 fps without going crazy on pressure, or is this a pipe dream?

Yes you can easily hit 2500 with 150's its not hard to go to 2600 with the 150's, going past that is trodding into some highpressure territory.
With the right powders 2400 is temptingly close with 170's.
The trick to getting the most out of the Ai is to use slow to very slow for the parent case powders. You must think out of the box as once you load that first fireformed case you're no longer dealing with a 30-30. The cartridge you now have to work with it something much more akin to a 300 savage.
If I were to do another ai conversion, I'ld first take the doaner gun and work up maximum loads with the ultra slow for the cartridge powders, looking mostly to accuracy first and velocity second. Then when the gun comes back from its rechambering you have load data to start the new cartridge with. Knowing that you can go up about 2-3 grs charge weight with the powders you already had data for,in the new cartridge.

Is it worth the effort and expense, I don't know. But I can tell you I've got more enjoyment out of this Marlin I had ai'ld than I would of had I of left it alone. Besides for the 100ish dollars for the rechamber and the 30$ for the dies, its given me alot of enjoyable time and experimentatiion with a new gun.

[pdawg.shooter]

Marlin says 42500psi is max on their action. Dont think I would try for 60000!

[O.S.O.K.]

Marlin says 42500psi is max on their action. Dont think I would try for 60000!

Yes, that's much more juice than I'd put into a Marlin. I've always understood them to be tapped out around 40,000 CUP - that must be 42,500 psi...

My handloads are targeted for that level.

[handirifle]

Marlin says 42500psi is max on their action. Dont think I would try for 60000!

No one suggested 60,000, at least I know I never did. I mentioned many numbers in my post, but if anything I suggested the Marlin's max is 50,000, not 60. I believe you'll find a closer ref to 50K PSI than 42 for the Marlin's max.

Max pressure on the Marlin (and other rifles) is based on many factors, but especially bolt thrust. The bigger the case at 42K the more thrust. The 30-30 case is much smaller in dia than the 450 and 45-70 and thus will allow higher pressurs, before bolt thrust starts to max out.

My references to higher pressures than 50K, were for the Win 94 BB only.

[arjunky]

The SAAMI specs for the 30-30 are 42,000 psi and the Marlin is safely capable of 60,000.

Handirifle, this is where you mentioned 60,000.

Byron

[O.S.O.K.]

Regardless, I think most AI conversions are a waste of time and effort but not the 30-30 AI - or the 25-35 AI - both are produce worthwhile increases in velocity right at the threshold that counts - IMHO.

[Mainehunter]

This discussion on AI interests me especially in the 30-30. This past summer I was toying on doing this conversion on a beat up Savage 1899 that I picked up. Unfortunately priorities got in the way of doing the conversion also, the barrel was cut down to 18.5" by the previous owner so I didn't know with the short barrel I could achieve higher velocities. One thing for sure it would make a nice brush gun!

Mainehunter

[NonPCnraRN]

I was thinking that a 30-30 AI in a 16" trapper would equal a reg 30-30 with a 20 inch barrel. That would be a good thing. If you could make up for the 4" less barrel and then some that would be a bonus.

[slimster]

I was thinking that a 30-30 AI in a 16" trapper would equal a reg 30-30 with a 20 inch barrel. That would be a good thing. If you could make up for the 4" less barrel and then some that would be a bonus.

RN, I have an idea that an A.I. Trapper would provide vel.'s similar to published ballistics for the 30-30, i.e. 150's @ 2400 and 170's @2200.

[handirifle]

The SAAMI specs for the 30-30 are 42,000 psi and the Marlin is safely capable of 60,000.

Handirifle, this is where you mentioned 60,000.

Byron

Well I missed that even on re-reading it. Sorry bout that. I MEANT 50,000. Thanks for correcting me. I will correct my post.

[arjunky]

The SAAMI specs for the 30-30 are 42,000 psi and the Marlin is safely capable of 60,000.

Handirifle, this is where you mentioned 60,000.

Byron

Well I missed that even on re-reading it. Sorry bout that. I MEANT 50,000. Thanks for correcting me. I will correct my post.

I was pretty sure you didn't mean that much for the Marlin.


Byron