I got a ar10 from the pawn shop I has a custom Krieger Barrel on it . Well I shot some factory federal premium 120 gr and it was blowing primers,so I called the pawn shop they said I'd has a tight neck chamber. So can u buy factory ammo for it or what kind of recipes do yall have that I could have loaded

Bring it to a smith and let him measure the throat and chamber. Could be a simple fix, Could be someone's riddens from a mistake.

Yes, there have been several neck dimensions on the 260. When Lapua brass came out, the necks were super thick and caused some issues. I have some once-fired Remington 260 Rem brass that will fit the tighter neck chambers. If you need some ammo with the bullet of your choice, let me know. I can load these for you. Lapua brass will be way to thick for the rifle.

Should be relatively easy to pull the barrel off an AR and have a smith touch it up with a reamer to current SAAMI specs.