TT,
A bore scope is the best way. I just had a put together Stevens 44 1/2, probably no 2 parts came from the same gun. The 25 rimfire barrel looked pretty good by eye, but a close look with the hawk eye scope show what looked like the surface of the moon.

You might have bet that it would scatter shots all over the place. The barrel was rechambered to 25-20 wcf and surprisingly it shot well! So, which is better, scope or eye?

Regards,
Ron