...............Most milsurp barrels that have seen any use in actual combat, or from places like South America will be less then new. Damage to the bore can take many forms. Some can damage the cast lead slug. Others that are very worn won't provide the guidance the cast lead bullet needs, since it's so much more fragile then a jacketed slug.Originally Posted by Hackleback
I have several surplus rifles with uniformly dark bores, but with good clear lands that shoot as well as a person could ask for. If your rifle has sharp lands and a good crown, the chances are excellent it will be a good shooter. Even if he lands are badly worn, it can still shoot, but the velocity will be limited. I have a 1895 Chilean in 7x57 whose lands appear only as shiney bumps spiraling up the bore. The leade apparently ends up under the rear sight someplace. But shooting to about 1600 fps it does a good job (with a Loverin design. No bore riders allowed )
However, there are no guarantees as there are just too many variables.
..................Buckshot