AR upper

[scott1911]

I'm looking around for a new upper for an AR project, and have seen some advertized as 'with M4 cuts'... What does this mean? and what are the differences between a standard AR15 upper and an M4 upper?

 

[toxic]

The M4 cuts are to make feeding more reliable. My understanding is that it is of little benefit in a semi automatic platform.

I'm in the same boat as you are. What I'm not sure about is if you have a M4 cuts in the receiver does that make a difference for what barrel extension you use.

 

[hbean]

It is refer to as "M4 feed ramp cut", the lower lip of the barrel extension is cut so it will guide the tip of the bullet into chamber lot smoother.

Google images of " m4 feed ramp cut" and you will see a few good examples.

 

[scott1911]

Awesome... Thank you guys. GOOGLED it and got all the info needed... LOL, should have just done that in the first place.

 

[ESQ]

They make no real practical difference. Especially in semi-automatics.

The only thing that is important about M4 feed ramps is that you must match uppers that have the M4 cut to a barrel extension that has matching M4 cuts. A rifle cut upper may be used with an M4 cut barrel extension but the reverse is not true.