A new M4 hits the market!

[mat10x]

If you have M4 feedramps, it's the first 1/16" below the receiver/extension parting line that's most important.
Even the shallowest M4 feedramped receivers will have that first 1/16".

The good, ok and bad are referring to the combination of barrel extension and receiver.
Note that the "bad" one has an M4 feedramp in the receiver, but a rifle extension that overlaps into the M4 cut receiver and creates a catch point for bullets, hence it's labeled "bad".
The good, ok and bad do NOT refer to the quality of the actual cuts, just the presence or lack of cuts.

ahhhh got it. i didn't realize the 1/16th is really all you need in the receiver part of the M4 ramp. good to know.

out of curiosity, what is the height of the M4 feed ramp receiver section of the M4 feedramp pic marked "good". looks like maybe 1/8th or 3/16ths...?

why is it that rifle feed ramps cuts do not need that 1/16" below the parting line with a rifle receiver? different angle?

thx for the great info!

[AR15barrels]

out of curiosity, what is the height of the M4 feed ramp receiver section of the M4 feedramp pic marked "good". looks like maybe 1/8th or 3/16ths...?

why is it that rifle feed ramps cuts do not need that 1/16" below the parting line with a rifle receiver? different angle?

Around 3/32".

Yes, they are a different angle by about 7 degrees.



Rifle actions function slower due to the longer gas tube.
This gives more TIME for the next round in the mag to reach the top of the magazine column and be stripped off the mag and into the chamber.
Carbines literally "out-run" the magazine and the extended feedramps let the round feed, even if it's not at the top of the magazine column yet.

[OldNavyGuy]

i had one that looked exactly like the one marked "BAD".., a Dremel and die makers files made it look similar to the M4 extension, receiver, only much smoother and polished to a near mirror like finish, never had a failure to feed since.

[Safetyhit]

If you have M4 feedramps, it's the first 1/16" below the receiver/extension parting line that's most important.
Even the shallowest M4 feedramped receivers will have that first 1/16".

The good, ok and bad are referring to the combination of barrel extension and receiver.
Note that the "bad" one has an M4 feedramp in the receiver, but a rifle extension that overlaps into the M4 cut receiver and creates a catch point for bullets, hence it's labeled "bad".
The good, ok and bad do NOT refer to the quality of the actual cuts, just the presence or lack of cuts.

Great post.


My two Colts have great ramps, but my Bushmaster's are not so great (upper left photo). In all fairness, the Bushmaster has never had a FTF or FTE after 4,000 plus rounds of 5.56, either. But it sure looks like they just make it by a hair...

[AR15barrels]

my Bushmaster's are not so great (upper left photo).
In all fairness, the Bushmaster has never had a FTF or FTE after 4,000 plus rounds of 5.56, either.

The net result is what's most important, not the path to get there.

[ballsout]

Great post.


My two Colts have great ramps, but my Bushmaster's are not so great (upper left photo). In all fairness, the Bushmaster has never had a FTF or FTE after 4,000 plus rounds of 5.56, either. But it sure looks like they just make it by a hair...

really? my bushmaster looks like the upper right photo.

[Safetyhit]

really? my bushmaster looks like the upper right photo.

Very interesting.

Mine is an A3 Izzy 14.5" w/ perm hider (16.1") I bought in '05. What is yours?

[AR15barrels]

really? my bushmaster looks like the upper right photo.

Either it's one of the Texas DPS ones from a few years back, or it's a more current gun.
The most current bushmasters seem to be coming with M4 feedramps.

[ballsout]

Either it's one of the Texas DPS ones from a few years back, or it's a more current gun.
The most current bushmasters seem to be coming with M4 feedramps.

Yes, I received it about a month ago.

[ARin]

ADS gone?