I bought this on a recomendation from my local "sportsman warehouse".They claimed that all thier military buddies use it to check "zero" in the field(I now doubt this statement as being valid).I struggled to get sighted in because of the lack of instructions. I checked "youtube" and could only find advertisements. There are however, several good instructional vidoes on "laser bore sights". I wish I had bought one instead.
Pros: easy to mount
Cons: unclear instructions
This review was written in the old system and had content requirements that are different than reviews written today.