As a matter of fact, it's not neccesary to check headspace on either Ruger 10/22 or Remington 597 when changing barrels. The way they're designed, the bolt is "self adjusting" for what tiny tolerances may exist. See-they're both blowback operation, as are all .22 semiautos. That means the bolt goes as far forward as possible until bottomed out against the rear of barrel, and headspace is "set" by the case rim relief in the face of bolt. That's why the factory rifles are designed for maximum reliability, but less than stellar accuracy. Again, when just swapping drop-in barrels, you do not have to check for headspace.
The rim relief on factory bolts is usually .048. Remember this is rim thickness. The maximum rim thickness of quality .22LR ammo is .040-.042, so facing the front of factory bolt back to where the cartridge rim relief or depression if you will to .043 will result in not only more accurate rifle, but it will also be less picky about different ammo brands/types of ammo. Remember-DO NOT ATTEMPT this if you don't know exactly what you are doing, of if you don't have access to an depth mic. Also when facing the bolt, it HAS to de done perfectly perpendicular to bore. If you try to do this and get it wrong, the rifle WILL go fullauto or even worse will detonate the cartridge while only partially chambered due to the bolt itself impacting on case rim, resulting in an blowout and possibly major injury. Facing rimfire bolts should be left for experienced people, and is but 1 of many tricks to get unbelievable accuracy from an semiauto. That is why I don't consider slapping an bull barrel & stock on a rifle is building it, but if that's all you can do, it WILL increase accuracy quite a bit from the extremely sloppy chambered factory rifles. I hope I've explained myself clearly enough for yall to make sense from my ramblings.
