The Barrel has a Bulge or is Bulimic:
A barrel with some light pitting inside shouldn’t be of too much concern. It should shoot fine and if it gets worse the gunsmith should be able to fix it easily. What you should be concerned for is larger holes that would hold a no. 8 or 9 pellet. If you see these walk away. Also, if there is any bulges in the barrel walk away because this could cause a misfiring or even a shattered barrel.
This especially applies to double barrel guns. If a double barrel gun has heavy or dragging trigger(s), be prepared to shell out some money for this to get fixed, it will be expensive. A single barrel trigger shouldn’t be too expensive to fix.
Also know as Damascus barrels, these are recognized from the twisting pattern of the steel. Watch out for these, they are more prone to be less safe with lower pressure smokeless powder. Don’t but these unless you are the man (and by that I mean - you know everything and you’re an expert on guns, which in this case you don’t need to read this post).
Make sure the stock is comfortable. Some older guns have an extreme drop at the heel; this may cause you to be uncomfortable. It is expensive and hard to bend these into a comfortable position. Stay away from guns that need restocking because it is usually more expensive than what you would get if you went right back around and sold it.
Check the Chamber Dimension:
Some older guns have 2 ½ or 2 9/16 inch chambers. It is difficult if not impossible to find ammo for these guns or to change them into modern sizes. These would be a definite “walk away.”
A used gun can provide lots of enjoyment to a shooter and a collector. Make sure that you follow these rules if you are going to buy one. Many guns are sold for cheap when they are used and many of these guns are safe, but those few ruin it for everyone. So always check it before you buy it.