Just got some MOE SL Mid Length hand guards for my rifle. Love the Hand guards and the slim feel is awesome. Question. Why do these Mid length hand guards us a ROUND HAND GUARD RETAINING CAP? Just about most Mid Length Uppers use a TRIANGULAR HAND GUARD RETAINING CAP. I wish this was stated before hand as a warning. Got the problem resolved, but figured people should know. Just checked out BCM Website for Mid Length Uppers and they all seem to have TRIANGULAR HAND GUARD RETAINING CAPS.