What barrel profile does the military m4a1 barrels have?
is it the medium contour barrel? or is it the thinner govt profile barrel? ( this is with regards to barrel thickness under the handguard)
Some would say that it is govt profile and others would say it is the med contour.
Before 2000 = government profile
2000 to now = the medium profile.
why did they shift from govt barrel to the med contour? the old m16a1 had a pencil barrel and they worked with full auto.
were there any problems with the old m4a1 govt profile? were there accuracy problems? over heating of barrel? didn’t the railed handguards help in cooling?
the increase in accuracy to the medium contour barrel is that significant?
M4A1’s can be ordered in either barrel profile by units.
The HB was developed since a segment of SOF was ruputuring their barrels with their excessive firing schedule.
ah… so up to today, there are still m4s running around with govt profile barrel .
was it the full auto firing that ruptured thier barrel?
IIRC - it takes more than 14 mags ripped off auto one after another to rupture.
More of a SAW usage than a Carbine…
Its not just the full auto, it was the higher volume of fire/daily round count. In an average day on a flat range, we put a little over 1k rounds though our weapons (depending on what firing table we are running).
All M4 (not M4A1s) have a govt profile barrel.
so when you say M4 it means govt profile 14.5 barrel with A2 carry handle right?
so all m4a1 are flat top with medium contour 14.5 barrel
is this correct? or were there m4a1’s that had govt profile.? any body can refute or agree to this?
All new DoD M4A1’s will come with the heavy ‘SOCOM’ bbl.
By the TM, the correct replacement bbl for an M4A1 is the heavy bbl.
A lot of SOF weapons are on a ‘heavy use’ cycle. The fire more rounds a year than your average unit might fire in 10 years.
oh ok. just wanted to know if there ever was an M4A1 with govt barrel. making a build right now.
I know the new ones have socom barrel.
Oh yes!
All of the original M4A1’s had the traditional M4 bbl. Many M4’s in SOF units still have them. However, on replacement they get the new bbl.
ah so All m4a1 come in govt profile barrel. and when they get a replacement… they get the socom barrel.
so basically no such thing as a bnew m4a1 with socom barrel.
A slight OT – would the barrel of an AR Colt LE6920/6921 be similar (or same) to the (military) M4? It has lesser weight on the specs sheet versus a Colt HBar (AR6721).
http://www.colt.com/law/lecarbine.asp
http://www.colt.com/law/ar15a3.asp
Actually, I don’t know that. I just know what I have seen in the Army.
no,
both M4 and M4A1 have a flat top upper…the main difference between the two is in the barrel profile (not always as said above) and the firing mode (burst vs fullauto).
an “M4” with fixed A2 carry handle is called “M16A2 Carbine - model 727”
alright… so Im building an m4 
and not an m4a1
And if you are using USGI (or equivalent) parts they you will have a perfectly fine service grade rifle.
usgi parts? you mean military surplus?
well… my lower is from an m16a1. only the upper and barrel is bnew. barrel is cmmg and upper is DD. does this count as usgi equivalent?
more or less. That barrel is probably not the mil spec metal, but it should be fine for a fun gun.