by MarkCO » Sun Oct 07, 2012 6:54 pm
The .450 BM barrel extensions have a wide cut (ramp) into them that basically removes much of the middle lower lug. All of the bullets I have tried have hit that ramp, not even close to the receiver. M$ feed ramps would be off to each side of the .450 BM bullet, so they would serve no purpose. With the .450 BM, it won't hurt if you used a receiver with M4 ramps, but you would gain nothing but a place to store crud.