Can save you ammo - Sightmark Laser Bore Sights

The 12ga model is aluminum body not brass as advertised. The battery cap can take a beating from the ejection system from a pump action limiting its overall life. But if you are careful (or don't close the action) it should pay you back in the price of ammo and frustration quickly. Can be difficult to see with open sights especially in the daytime; works much better with a scope. Could try boresighting with an old license plate maybe (very reflective surface). I used to boresight 2 mossberg 535 shotguns with rifled barrels.
Pros: Easy to Use
Cons: 12 GA is Aluminum not brass, batteries go dead fast!

This review was written in the old system and had content requirements that are different than reviews written today.