Benjamin Mag Specs
The O-rings are standard sizes, # 010, 009, and 008.... so the bolt nose is 1/4", 7/32", and 3/16" respectively.... I use MRod magazines on my Hayabusa and Disco Double, and there are a few things you need to know, however.... The .177 and .22 cal are the same thickness (fore and aft) and are interchangeable on teh outer dimensions, but the .25 cal is thicker (about 0.070" IIRC).... The .177 and .22 cal fit on a 7/16" boss on the barrel, but the .25 cal barrel (and the magazine recess) is 1/2" OD.... The hole in the magazine is 1/64" larger than the ID of the O-ring so the bolt slides easily through it.... The magazines are all the same height and diameter, although there is a smaller one, the 8-shot .22 cal one for the PRod.... It is in between in thickness compared to the others, fits on a 7/16" barrel, and the slot below the barrel is shallower.