30-30 Ackley Improved

[william iorg]

My goals forvthe .30-30AI in the 20" barrel were
3,000fps with 110- grain bullets.
2,700fps with 125/130 grain bullets.
2,500 fps with 150 grain bullets
2,300 fps with 170 grains bullets
It proved easy to exceed all of these velocity goals with good case life using a wide variety of powders.
A good Improvement with little effort.
I will say this. Today with the availability of the .308 Marlin Express there is little need to ream an Improved .30-30 chamber except for curiosity

[Malamute]

IT SOLVES ANY AND ALL OF THE 30-30 CASE SHAPE PROBLEMS...

All right, I must admit I don't see that the .30-30 has any case shape problems. About the only thing you can change is to blow the shoulder forward, but you don't pick up much capacity in doing so, say 1.5 gn. The Powley computer figures you might pick up 1% more fps, so I'm mystified as to why make such a change.

Karl

It does more than that, it reduces body taper also, which reduces bolt thrust. Read Don McDowels post above. And William Iorgs posts.

[TedH]

IT SOLVES ANY AND ALL OF THE 30-30 CASE SHAPE PROBLEMS...

All right, I must admit I don't see that the .30-30 has any case shape problems. About the only thing you can change is to blow the shoulder forward, but you don't pick up much capacity in doing so, say 1.5 gn. The Powley computer figures you might pick up 1% more fps, so I'm mystified as to why make such a change.

Karl

It does more than that, it reduces body taper also, which reduces bolt thrust. Read Don McDowels post above. And William Iorgs posts.

You pick up more than 1% velocity too. With the reduced bolt thrust, it is safe to load to higher pressure than the standard 30-30. That's where the gain comes in, not from operating at the same pressure with just a tad more capacity.

[Mainehunter]

From what I have read and was told in the past the barrel length needs to be a minimum of 24" for the AI to work at it's fullest. Is that a myth or truth to that

Mainehunter

[BAGTIC]

If people are getting 200-300 fps more velocity from the 30-30AI than from the 30-30 it is mostly due to loading to higher pressures. The small difference in case capacity would not produce that much increase especially in the shorter barrel lengths common to the calibers.

[BAGTIC]

The reputed problems with the original 30-30 cartridge were not due to case design. It was due to the design of most of the rifles in which the cartridge was chambered. The springy action of most lever action rifles allowed the cartridge base to be set back under pressure thus lengthening the case. When the pressure was released the action retracted to it normal configuration which forced the now expanded case forward. Driving a tapered object into an undersized hole producing a wedging action.

If the front end of a dry cartridge is expanded tightly enough to grip the chamber wall and prevent the case from moving backwards the rear part of the case which requires greater pressure to grip will be pushed back as the case stretches. This stretching is the basic cause of eventual case head separation.

[KWK]

It does more than that, it reduces body taper also, which reduces bolt thrust. Read...

Let's see, the body taper on the standard .30-30 is .40 deg and on the Ackley it's .36 deg (based on the Ackley drawings I could find). This is supposed to dramatically decrease case thrust?!

You might read Barsness' article in the 10/13 issue of Handloader. There is lab evidence the AI shape doesn't affect breech thrust at all in the bolt guns which use it. While they didn't experiment with lever actions, I doubt there will be much difference. He did acknowledge the wedging effect of a long, tapered neck in a springy action, though.

The AI gives more fps simply by running pressures up to well beyond factory levels, and since I don't buy into the reduced breech thrust argument, I can't see this as being for the best. Given the basic action handles the .444, I do think you'll get away with it in a 336.

Karl

[william iorg]

All you need to do is purchase a .25-35 Thompson Center barrel. You experience the onset of sticky extraction with factory loads. With the Improved case you can equal and exceed 250 Savage performance with no extraction issues. The easiest way to see Improvement is with rifles having little primary extraction.

[KWK]

... with no extraction issues.

Do extraction issues only indicate breech thrust, or does the fact a tapered case makes a better wedge than a cylindrical case also come in to play?

Barsness noted his 99 in .250 will lock up with hot loads. His .22-250 front locking bolt guns won't with even higher pressures, yet the case taper is the same. His theory is the springy 99 action will not only widen a case but lengthen it as well, and when the pressure is removed, the action shoves this now bigger wedge into the chamber: Stuck. The Contender must be at least as springy as a 99, and the .25-35 has about the same case taper.

Barsness' tests don't make for the definitive answer, but I think he's on the right track.

Karl

[william iorg]

The Contender is a bit springy. A "Plug" is a good way of describing the case except the 25-35AI. Loaded to high pressure can be inserted into the chamber and the chamber closed on the fired case.
Another description could be the .307 Winchester which will exhibit lever kick with high pressure loads on hot days. The .30-30AI does not exhibit lever lever kick at the highest load levels.

[KWK]

The drawings at hand show the .307 to have about the same taper as the .30-30, which is to say it has about the same taper as the .30-30 AI. It does, though, have about 25% more cross section than the .30-30, and at a given pressure, it will shove harder on the breech.

[siberian505]

Mine is a 64A. How about a 200 grain bullet at 2200? The bullet is a NOE mold, solid, cup point and hollow point. Prairie dogs and rockchucks beware when done of the snow melts!!!!!