M4 Feed Ramps?

[porscheboy]

Hey everybody, just finished my lower, and now moving on towards the upper. Ive noticed that there are two types of upper receivers... M4 Feed ramps and no Feed ramps. Does an upper with feed ramps determine what kind of barrel I need?

-Thanks In advance

 

[MarshallDodge]

There is a barrel extension on an AR15 barrel that can have M4 or the old standard rifle style feedramps. You should match the barrel to the upper because of the way the feedramps are cut.

 

[Bartholomew Roberts]

M4 upper with M4 barrel extension = go
normal upper with M4 barrel extension = go
M4 upper with normal barrel extension = no go

As a general rule, the M4 feedramps are desirable, though some argue that the steeper angle of the feed ramp is harder on match bullets and bullets with no cannelure.

 

[Onmilo]

It is the other way around Bartholomew.

M4 feed ramps were designed to prevent bullet damage during full auto feed cycle.
It was later found that the M4 style prevented bullet set back using the uncannellured 77 grain Sierra bullets by angling the feed more into the chamber so the slightly longer round did not first impact on the chamber roof.

Because of the advantages, M4 feed ramps were incorporated on all new production M4 Carbines.

The standard M16 has not exhibited the feed issues the Carbine has regardless of the bullet type utilized and it was deemed unnecessary to incorporate M4 feed ramps on full size rifles.

The 18" barrelled Navy/SOCOM rifle does incorporate M4 feed ramps in the design.

 

[porscheboy]

Thanks everybody for the comments, ill post pictures of my build soon.

 

[RockyMtnTactical]

It is the other way around Bartholomew.

Bart got it right.

 

[Pony Express]

I strongly recommend m4 ramps. while the difference in reliability is insignificant for most users (myself included), the real benefit comes when purchasing replacement barrels. It's much easier to find barrels with M4 feed ramps as opposed to no ramps at all.

 

[mshootnit]

I believe that the m4 ramps also make the rifle more reliable with questionable mags.

 

[Zerodefect]

M4 ramps are needed for 6.8 and 6.5 spc and longer handloaded 5.56

They don't hurt to have. Why every AR deosn't come with them is a mystery to me.