We really need more 3" actions for a number of rounds. My Roberts is in a LA and the way it was set up by a real master smith, it's one of the slickest feeding rifles I have, no matter how the rounds are positioned in the box mag.
DF
There's still a few Yugos floating around that won't break the bank. They aren't full length actions and are designed for the 57 MM case which still allows seating bullets out further than the Remington 700 Short Action. I built my AI on one. However I would like to make a recommendation. Don't use the Ackley Improved reamer. Try to find the RCBS reamer. It doesn't have quite the angle on the shoulder and the rounds will chamber better than the Ackley without any alteration. I had to file a little off the inside of the extractor to make the Ackley work.The amount of powder difference is negligible with the RCBS. If I had it to do over again that's what I'd use. Doesn't look quite as sexy as the Ackley, but I'm more into function than looks.
I had Ray Montgomery rechamber a Savage 99CD from 250-3000 to 257AI a couple of decades ago. Ray recommended going with the standard 257 because he was concerned that the 40-degree shoulder of the AI case would feed poorly. I still believed that a little extra case capacity would result in a meaningful increase in velocity, so I ignored Ray's advice and had him make it a 257AI. It feeds OK, but probably not as smoothly as it would have without the sharp shoulder.
I think that if I was going to build a 257 Roberts or 257AI on a long action, I'd choose the path of least resistance and make it a 25-06 instead.
