308 Ackley Improved in Contender?

[Robert]

My New Contender  Loadbooks USA has loads listed for the Contender in .308.  In the past, I heard that both the  .308 AND 7.62x39 were too much  for the Contender because of the amount of taper in the case causing excessive.  What about a 308 Ackley improved?  Would this work, and IS anyone chambering it?

[Nobade]

I can't imagine that any responsible load book would list data in .308 for a Contender. I just wonder if they are combining Encore data in that book as well? As for 308 AI, I doubt you'll find any responsible gunsmith willing to do that. What you could do, however, is short chamber a barrel for it, and grind down your dies accordingly. You'd still have to be pretty conservative with your loads, but you would end up with something about like a .309 JDJ. But a full length version? Not a good idea since somebody could chamber a factory .308 round and really ruin their day.

[John Traveler]

I dunno what you would hope to gain by making the .308 Winchester an "improved" cartridge.  It's alrealy close to what most "improved cartridges" are:  short neck with sharp shoulder, minimum body taper, and close to optimum powder capacity for it's bore size.

The .308 W is not chambered in Contenders for a simple reason:  the gun won't hold up to extensive firing, and will result in the lockup loosening, stretched frames, and other bad things.  This is not a function of it being a tapered case, but because of the high SAAMI pressures it's loaded to, and the large .473" case give lots of back-thrust on the breech.

Other big cartridges use large, minimally tapered cases too: .444 Remington Magnum, .454 Casull, .45 Winchester Magnum, .300 Savage, and so on.  But the .308 Winchester has the highest standard SAAMI pressure, and combined with the .473" case head, and enthusiastic handloaders, can easily lead to BIG PROBLEMS.