How hard is it to replace a garand barrel?
Just takes a barrel vise with the special bushing and an action wrench.
The barrels are timed so the new one just threads in and should stop in the right place.
Then you use a pull-thru reamer to finish ream the chamber while the new barrel is in the action.
The bolt applies cutting pressure to the reamer while you turn it with a rod sticking out of the muzzle.
When the bolt cams closed, stop reaming as the chamber is just the perfect depth now.