I've done a few swaps like that. Here's a write up I did on one of them:
.20 Dasher Mongrel build part 1.
It's long, in four parts, but it does go over the process and what to check and ways to do it without using any gauges. Besides swapping a few barrels onto factory 700's, I've replaced barrels on some Savages and several custom actions and have never felt any need for head space gauges. Nothing wrong with using them, but if you don't have them, it's not hard to get the measurements needed without. Fitting for a particular lot of brass, anyway.
- DAA
