My take on the venerable Rem 722 is a bit different. Remington adapted their Rem Rob'ts 257 into it. But adapted is the key word, here. The 6mm Rem is right on, and the 7x57 is too long. If you have a 1 in 10 twist bbl., I'd suggest going to a 25x284. This case is only 55mm long. It was designed from the git go to have bullets seated deeply. Remington's factory load for the Roberts was a longish round nosed H.P. bullet, at 120grs. IIRC. I recall using a 100gr. spitzer in my 25-284, on a full length Mark X action, and it was a handful. But you can do 100 to 120gr. bullets in the shorty 722 with aplomb, using the 284, or more recently the 6.5 Norma, necked down to .257". But if you want to be able to shoot factory ammo, then the Ackley version of the Rem Roberts 257 will be the answer. But be aware, that there are still true 257 Roberts reamers out there. An Ackley version of one of these will cause case head separations with the factory Rem Rob'ts ammo. I saw a couple of cases that came apart half way down their bodies. Since it was his wife's rifle, my suggestion was for him to go over to a bin of nickeled 7x57 cases, buy a hundred of them, and then neck them down to the original 257 Rob'ts shoulder lengths. So, if I was to put a 257 Rob'ts, into a 722, I'd make sure it was a Rem Roberts, and then I would leave it stock. What you would lose in velocity, you'd pick up in penetration. My 100 gr. bullets out of the 25x284 at 3500fps, were too light and too fast for Elk. But reading the Robert's field records, show that it was about the lightest big game cartridge readily available back in the fifties. The little 722 was just right for me when I was twelve years old, and fresh out of Hunter safety class, in 1959. Although mine was chambered in the 300 Sav..