It's probably a stupid question, but can this be done without removing the barrel from the receiver?
I spoke with an old armorer about "counterboring barrels"
He was a "field" armorer or tech in today's terms.
He told me they often had barrels come in that had muzzle issues, but nothing else wrong with them.
They did most of their work from the back of a truck, fitted out with a parts bin, tools and maybe, a small lathe and for sure a drill press.
He told me they had a clamp made up for the adjustable height plate for the drill press that would accept the barrel, after the barreled receiver was removed from the stock. They put the barrel muzzle through the plate and attached the clamp, then clamped it onto the plate.
The next step was to use an appropriate drill bit to cut a hole deep enough to clean up the problem.
He told me they usually went down a minimum of 3cm but sometimes as much as 5cm, depending on whether they had spare rifles on hand to issue.
He was German, I suspect the Soviets and other combatant amorers did similar things to keep the rifles in use.
Cutting off the barrel and refacing isn't the only way to cut a new crown.
There are other methods as well, but doing it properly on a lathe, is still the best way.
