I prefer the last picture to the one above it. The notch allows another turn and you can see the top of the tube can catch on the BCG when pivoting the receivers. Also the notched tube looks like a cheaper commercial model. The unnotched tube is milspec.
The biggest issue with assembling an AR isn't so much getting the parts together right - it's getting the right parts together. You'll remember the quality of a gun long after you forget how much you paid for it.
US Army 1966-69, VFW Life Member, Retired Geek
Last edited by Quentin; 01-27-2013 at 04:47 AM.