I am a bow hunter who started gun hunting a couple of years ago but am still new to alot of it. I bought a 12 gauge mossberg 500 for myself and 20 gauge for my niece from Wal-Mart in 2006. We have put the smallest rings available (in terms of getting the scope as close to the reciever as possible)on both guns and taken it to the local gunsmith who shims them and givesthem back to me every time and saysthey are fixed but at 50 yardsI am still a 12 inches low on both guns. If anybody has any kind of ideas or a solution to our problem I would greatly appreciate any help.