most of my ar-15 types have the regular barrel extension and the regular upper.
lately lots of barrels and uppers come with the m4 cut feed ramps.
now i just ordered the DSA a3/m4 upper form AIM the other day and my barrel isn't in yet so i may end up with regular extension and a m4 upper that will need to be re-shaped to the m4 ramps.
now i know some places cut in m4 ramps in regular extensions all the time and it don't look to be much of a job.
anyone cut their own ramps into the extension??