Ackley Cartridge Life

[rodwhaincamo]

I read through some older posts and it seems that some claim cartridge life is extended.
This doesn't make much sense to me as AIing the chamber should actually be spreading the brass thinner.
What say you oh knowledgeable people?

 

[William T. Watts]

Ackley Chamber

I would think that a cartridge case that starts out as a standard case if fired in a Ackley Improved chamber will be thinner in the shoulder. I additionally think that a Ackley Improved case (280 Ackley comes to mind) should have a normal 3-5 firings depending how heavily it's loaded. A True Ackley chamber is cut to a - .003" shorter than a standard chamber so a standard round can be fired in the AI chamber. There needs to be a bit of resistance as the bolt handle locks into battery so the round is held securely against the bolt face and stretches in the shoulder and not in the web. I don't really think there is a clear cut answer to your question, however anyone who wants a Ackley chamber in my opinion will load the round as heavily as possibly within reasonable pressure limits. I've never owned a rifle with a Ackley Chamber nor cut a Ackley chamber, however, I do not think it would be any more difficult to cut than a standard chamber. My .02 William

 

[wncchester]

"I read through some older posts and it seems that some claim (AI) cartridge life is extended."

Yeah, that is often claimed isn't it? It's supposed to come from the sharper shoulder angle but there is no case life magic in chamber shape. Fact is, case life depends on two things;

1. How well any sizer die matches any given chamber. (And that's pure luck, not the price of the rifle or color of the die box.)

2. How the loader controls the sizing. Most reloaders excesively resize and doing it right is a skill often missing.

Some claim high pressure loads will fatigue cases but that's incorrect too. At something much lower than half of normal rifle pressure a case will firmly fit the steel walls so additonal pressure won't mean a thing to it as long as the chamber stays in one piece!

Case wall thinning obviously occurs but it's effect is trivial. The AI conversion adds some benefit for a few cartridges, the .257 Roberts is one, but is virtually worthless for most. And Ackley himself said that.