Seems like my B-Square saddle mount came with spacers for a 20 ga. I didn't like and just wound get it drilled and tapped. I do have one of the rails that mounts on the rib I will give you it you want to try it. I just never got around to trying it out and went with a drill/tap on my 870 and my son's 1187.


"Any way you look at it, most of the problems facing baboons can be expressed in two words: other baboons" -
D.L. Cheney and R.M. Seyfarth