Hey,
Second AR build is a 350 legend pistol, 7.5" barrel (wanted 10-12 but couldn't find one). I originally was planning 300 BO, but 350 ammo seems to be easier to find (wal-mart for $10/20). I have a carbine length buffer tube and spring with a 1.8 oz weight but it's still undergassed and short stroking. I ordered a lighter buffer spring, hoping that fixes the short stroke. Any other ideas on what to do? I did have a pistol buffer tube and spring on it at first and it worked fine, but it was slamming back pretty hard. It's a neat little AR, just hoping to get it to be semi-automatic!