This mount and scope have been laying around for over a decade after finally realizing it was atop some kind of Beeman R series rifle. There was a time when I could not find a mount to reliably hold scopes on magnum springers. This was during the late 90's that this mount with stop pin came to my attention. In desperation, the Beeman literature said this was the most solid mount available - so I tried it. It too had issues, with even the stop pin marring one of the receiver holes. Removed the Leupold 3-9x33 scope from it's grip, and will be happily selling it in the near future. Do any of you still use mounts with stop pins? Cannot wait to get rid of this one, and they still sell for $60 new!
I have used the Beeman/Sportsmatch one and two piece mounts with stop pins with good success. I have not had any of them fail me. I do make sure the stop pin is seated completely and then I make certain the stop pin is fully to the rear of the gun and then tighten the mount.
I have used some other mounts with stop pins and they have worked well also.
God Bless,
Scott