How to counterbore a barrel?
Bought an old mauser, the bore is dark but still have some shine and rifling is distinct. Noticed the rifling near muzzle is almost gone, drop a bullet with rear end first and it will go in almost 3/4" and stop. I have not shot it yet, but think I may need to counterbored it. How to do it without a lathe? Can I use a handdrill and a regular drill bit? How much oversize and how to remove burrs after counterbore? Thanks.