Badly worn bores will usually not shoot cast bullets well, while a simply worn throat in a rifle bore usually shoots cast bullets even better than when new. Worn bores or throats can still shoot jacketed bullets quite well.

I have a Palma match barrel that went through roughly 15,000 rounds of hard-ball 7.62x51, which burned out about 8" of rifling at the origin. It was still shooting 180gr. MK's into 1" at 100 meters - not good but not spraying them either.

I shortened the barrel by 4", re-threaded it onto a Mauser action and chambered it for a little wildcat I'd thought up to duplicate the .30BR. I still have that barreled action and although there is no rifling for about 1 1/2", it shoots 1/2" with 130gr. to 165gr. bullets.

So - you have to shoot it to find out. Small bores usually fair poorly with less "wear" than larger bores, showing flyers and greatly expanded groups with wear that larger bores shrug off.

The larger the bore, the less effected they are, generally speaking.