Re: Judging Temps
Rule of thumb: if you can't comfortably hold the barrel, it is too hot.
Every barrel has it's own quirks. Some move a lot when they warm up, others shoot fine with a slight reddish glow.
The cooler you can keep the throat, the longer that barrel will last and shoot accurately.
For a 308 type case, I would stop after 5 rds in the summer time. 223 case, probably 10 to 15rds. With a magnum, three rds is pretty toasty in most hunting type barrels.
If you see groups grow as the barrel heats up, I would shoot my groups as 3 - 2 rd sessions on the same target. You will have 6 rds in your group and the barrel will stay cool throughout.