I will respond as follows...the first barrel swap I did was a 308 that I swapped to a 260Rem, bought the head space gauges which were in common. Once I realized what Head Space was all about, as a result of that build, I never bought another set of head space gauges. Head Space is a chamber setting that insures a standard cartridge will fit in it. It doesn't matter how that is done, just so we get it right. The way I get it right, I take a case out of the box of cases that I am going to reload, set the head space to it with the nut hand tight, then see if the rest of the box of cases will cycle through the chamber. If I find one that is more snug than the rest, I reset the head space to that one, and make it permanent. Then I load that batch of cases with the intent of the first firing to be fireformig, although I do shoot for groups to gain all the information I can from that batch. People pay extra money to get tight chambers. Once I fire a case in a chamber, "I have a tight chamber"! From then on I neck size only until my cases will no longer chamber. So far that has averaged out to be about 10 reloads. I can understand bumping shoulders with gas guns, but not bolt guns. After shooting, the first thing I do before packing up is make sure all my fired brass will cycle through my chamber, then I know I am good to go with neck sizing. I don't see any advantage to using a fire formed case to set the head space, and you could end up with a "wildcat" chamber in which a factory load could fail to fire?
There has been so much written about head space, bumping, measuring, special tools, etc., that confusion abounds. It is not that complicated, especially with bolt rifles.
This is how I do it, and I hope I didn't "rant" too far off the questions being asked...Jim :-)
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