Quoted:
I am just building an AR with a 16 inch barrel and collapsible stock. I just looked at my upper and it has no feed ramps at all, just a perfect circle. How do I go about getting the feed ramp cut into it? Thanks Guys for all the help.
Steve E............
as the graphic i posted notes... using either a rifle cut or an m4 cut barrel will work fine with a receiver without cuts. so your good to go. no need to cut anything.
and before you say "but but m4 cuts are better!.... or even if they aren't i want them anyways!... or dammit the chart tells me m4 cuts are desirable!" or anything like that - do not cut your upper... you will weaken it and go through the surface hardening.
if you absolutely insist on having a upper with m4 cuts (which you DO NOT need... unless you are running full auto) then place your upper on the EE for trade or sale.. then buy another upper with m4 cuts.