Attaching a front sling mount to the Sig 522 has been causing quite a bit of confusion for some time now. This blog entry is to answer some questions and give at least one solution. I wanted a swivel QD (quick detach) mount to accommodate a 1.25" sling width.
First off, some technical info:
- The faux gas block on the 522 is outfitted with 10-32 threaded holes on both sides.
- The depth of these holes is .4575 inches deep.
Ace model UMPB-A202 comes complete with the QD for 1.25 inch strap, a 10-32 flat head screw, and a 10-32 nut.
The threaded holes are .4575 inches deep and, fortunately, the flat head screw is short enough not to bottom out in the hole.
Hope you found this information helpful.