Rifle barrel question

[gburner]

What does it mean when a rifle barrel is 'counter bored'? How would I spot it in a potential purchase? Thanks.

 

[critter]

Many military surplus rifles (Mausers, MN's, etc) have rifling damage at the muzzle by improper or overzealous cleaning procedures. If that was so and the rifle was refurbed, sometimes the bore at the muzzle was drilled out (enlarged) back to where the rifling was good. That left an enlarged area at the muzzle that the bullet did not touch on its way out.