How to Inspect a Rifle Bore

Inspection

Find a clean line of sight into the barrel from the bullet's point of entry for a naked eye inspection. Request permission from the gun seller to remove the bolt assembly, if applicable. If you are inspecting a break-barrel gun, simply break the barrel to obtain the proper line of sight. Now, peer down the barrel. If this is a rifled bore, look for even and smooth rifling without signs of wear or inconsistencies. If you're looking down a smooth bore barrel, like that of a standard shotgun, look also for inconsistencies, dings, or worse still, dents. If any of these are visible to the naked eye, the bore of the gun may be mildly to severely compromised.

Test for bore cleanliness and inconsistencies that may be hidden by rifle oil. Ask the seller for permission to run a cleaning patch through the gun. If the patch comes out mildly to significantly dirty it is an indication that the gun, and so the bore, has not been cleaned recently, and may not be cleaned regularly. This can lead to bore irregularities.

Ask the seller's permission to clean the barrel and bore. Run patches with solvent through the barrel until they come out clean. Do not oil the gun. Run four to five more patches through to dry the barrel and then check for inconsistencies with the naked eye. With the bore oil-free, dings, grooves, gouges and dents are going to be more visible.

Examine the bore with a bore scope, if possible. If the gun is high-priced or you are particularly concerned with the state of the bore, this is where a bore scope comes in handy. The thin fiber optic tube can be inserted into the barrel to get an up-close, 365-degree image of the barrel. There are also models and accessories designed to follow the rifling. This tool and technique is considered the only surefire way of discovering nearly all bore ailments and inconsistencies, though it is still not foolproof. A modern bore scope can run between $1,000 to $2,000, so it is rare that the average gun owner or even gun buyer has one.

Tips

• Ask the gun seller what type of ammo he usually uses with the gun. Inconsistent or pre-NATO ammo may be warning signs of bore inconsistencies or wear. Ask the gun seller how often he uses and clean the gun. Overuse or under-cleaning is another tip that the bore may be damaged.