I've gone through every Allen key I have (not many) and none of them fit. It's smaller than the mag reg adjustment key which seems to be a common size for everything else in my arsenal. It's not the same size as the grip frame screws, that's 3/32's (same as the X-Valve regulator adjustment screw)
http://ecx.images-amazon.com/images/...500_AA300_.jpg
Anyone happen to know off hand?