I've heard a bunch of stuff about which ammo to use in this gun. It has the old .317 I can't remember if that means it's An 's' or a 'J', I used to just buy fatory 8mm[ which was mid-way between s and j. But now I understand all 8mm is .323. They [ammo manufactors] made their 8mm to safley fire in both the S and J version years ago, but the last time I bought some 8MM, I had a hard time openning the bolt. Classic example of too high pressures. But before that, the gun handled any COMMERCIAL 8MM I put in it. I have to say I only shoot the gun on rare occasions and the last 2 boxes of ammo were at least 15 years old. They were Remington 8MM. The new box is also Remington. Am I done with this gun?