Barrel swaps wiht savage are easy provided you have a barrel nut wrench and some way to hold the barrel. [ barrel vise] Clamp the barrel , not the action, smack the wrench and unscrew the action.
Technically you need a go-no-go gage to set head space. I just use a fired case from a known good rifle. Screw the action down on barrel with the bolt and fired case installed. Tighten the barrel against shoulder and back off just slightly.Tighten shoulder nut and go shooting.
You will need another bolt face to go from 7mm to .308. These are available from Midway, Brownells and Savage. They also have the tools. Once you have the tools you're in business. Takes longer to remove stock and scope than to change barrels.
Have fun...Goldy
