M4 feedramps

[RWBlue]

Sanity check

Upper with M4 feedramps with a barrel that doesn't have M4 setup = not ok

Upper with out M4 feedramps with barrel that has M4 setup = OK

Correct?

[Onmilo]

Barrel extension, not the barrel proper, has the feed ramp modification.

Modification extends onto rear face of upper receiver.

Either barrel could be used on either upper but you will sacrafice any feed advantage by doing so.

A barrelled upper with the feed ramp modification is considered to be one component part.

Change the barrel for even another feed ramp modified barrel and you change the geometry and alignment of the relief cuts.

Colt strikes again,,,,