Head space? Checking head space? How many ways? I do not know, I do use three different methods/techniques without purchasing an over the counter gage, I prefer all of my methods over the commercial version(s), I check head space in thousands, commercial versions are go, no and beyond.
Off-setting head space on a chamber with a rim, try finding cases with thicker rims, try to determine the length of the chamber from the bolt face to the shoulder of the chamber then learn to measure case length from the head of the case to the shoulder of the case, then the tricky part, adjust the die to prevent shoulder set back, this method is more effective on cases with shoulders, but not as effective as on cases with long tapered bodies like the 303 British, 30/40 Krag, 300 H&H 30/30 etc. It becomes an either/or, head space on the rim or head space on the shoulder, it takes a very good die and chamber to do both (or get both close).
Then there is the set the barrel back or find a way to move the bolt face forward? A friend had .007 head space on an 03 he was building, the problem ? it was a period correct 1911, he had 80 plus bolts, I had 30+, I offered to check all 100+ bolts for the effect each had on head space but even if one was found to reduce head space it would not be period correct and all 100+ bolts could be withing .0015 of each other, and there is no promise another bolt will reduce head space.
F. Guffey