How to Inspect a Barrel

CoyoteKiller, of SKSboards.com, states:
Take a good bore light with you and it will be no problem to spot a bad bore. The critical area to check is the lands right in front of the chamber. Usually if there is any damage it will be there. Also check the crown of the barrel for any nicks or anything. A good gunsmith can recrown a barrel for a nominal fee.

TiredOldFart, also of SKSboards.com, adds:
Good advice. The only thing I would add would be to take a good look at the rifling in the last few inches of the bore (from the muzzle end).

The first thing is normal wear. The last few inches of the barrel will have more wear than the rest of the barrel (other than throat erosion at the chamber end) due to the simple fact that the bullet is travelling faster as it moves toward the muzzle. It is at its maximum velocity at the very end of the muzzle. The faster it is going, the more friction there is. The more friction, the more heat, and the more wear.

The other factor is careless cleaning. Countless barrels have been destroyed by frequent vigorous cleaning. The cleaning rod scrapes along the rifling, and gradually wears it away.

You always want to use a bore guide when cleaning from the muzzle end. (At an absolute minumum, on a VERY infrequent basis, ONLY when absolutely necessary, you can try to pinch the rod at the muzzle end with your fingers, and wipe the bore slowly and carefully. As careful as you are, you are still likely to scrape it once or twice (or more) -- and the smaller the caliber, the more likely the risk of scraping it.) This emergency tactic should be reserved for true emergencies, like if you shot some corrosive loads and your bore guide was lost, and you are faced with a choice of guaranteed damage from corrosion, or possible (or even likely) damage from cleaning without bore guide.

Naturally, you should first attempt to clean from the chamber end under those circumstances if at all possible. (And even at that, be very careful at the end of the swipe-cycle, after your brush or patch has cleared the muzzle, while you are reversing rod direction to pull it back through to the chamber end. You don't want to let the rod scrape the sides of the bore at that time either.)

More In-Depth Barrel Inspections

Slugging a barrel provides the ultimate knowledge of the interior condition of your barrel. However, it is very unlikely that you will do this on a regular basis or be permitted to do so prior to purchasing a gun.

-- SeanNewton - 30 Dec 2005