Head Space gauge VS once fired full lenghted

[eddiesindian]

Headspace is not the boogeyman! If you have ever fooled with Thompson Center single shots you know that every one of them has a different headspace because of the frame barrel gap. Now how much you bump the shoulder back, thus changing the headspace, will have an effect on accuracy. Some guys FL every round but are very careful to keep the shoulder bump at .001. I am of the school of fire forming and then just neck sizing either with a collet or neck die until I get resistance, then it is time to FL and anneal. Usually 4-5 reloads. FW Counch gave you good advice. Headspace is that measurement from ogive to base so commercial ammo will fit in more than one gun. Never checked, but I'll bet the tolerance is +/- .005. That's why I reload, to reduce the tolerance to as near 0 as possible.

I wasn't asking for advise or how to,s... I asked specific questions. You may reconsider what you call head space. Base of cartridge (breech ) to shoulder of case is head space. Ogive to base as you've mentioned would be more of a C.O.A.L. if that's where you measure it which is where I do for seating depths. but thanks anyway bsekf. Don't own a Thompson single but I did however purchase there very 1st semi 22LR rifle. Man I love that rifle.