The thread is a little stale, but the problem still exists, so I'll add my experience. I tried the Seekins selector switch with the Hiperfire X2 in my PCC, and it is unsat in 90 degree mode. As an experienced soldier, I don't feel completely right with a 60 degree throw. There are two fault modes. One, safety does not fully pop to fire under detent power because the back of the hammer catches the flat on the safety barrel. A hard trigger pull overcomes the incomplete rotation of the safety, and the gun fires normally after that. Two, when on safe, the distance from the back of the hammer and the safety barrel is too big. Yeah, stacking tolerances, I know, but Aero precision does an exceptionally fine job of manufacturing within the spec. So if give the trigger about 7 lbs of pull with safe on, the spring mechanism pushes over center, and the safety claw catches the hammer. No fire, but need to cycle the gun to reset the hammer.
On close examination, it is my opinion that dual-cut safety barrels (60/90) will not work with this hammer, but milspec will, so I am assuming any single-cut safety will work. The problem is obviously the cut of the safety. YMMV.
