BCM Upper Receiver Groups
Professional Grade Weaponry
M4 Feed Ramp Barrel Extension (USGI)
M4 Feed Ramp Flat Top Receiver
In developing the USGI M4 carbine as one of the primary weapons for today’s infantry, some modifications were performed to the original M16 platform to enhance the reliability of the shorter barreled carbines. With the shorter carbine gas system and the increased gas port pressure, the carbine cycled faster, and at times the cycle rate could be faster than the magazine would feed ammunition. One of the modifications done to increase reliable feeding included enhancing the angle and the length of the feed ramps. This USGI modification was done to both the barrel extension and the upper receiver, creating a longer and steeper feed ramp. These Mil-Spec M4 feed ramps are part of the original CNC manufacturing process. As a result, the factory machined M4 feed ramps on the receiver are hard coat anodized which adds significant strength to the aluminum. This feature is offered on all BCM uppers and all BCM barrels.
T-Marked Upper Receiver
The contemporary M16/M4 rifle is built around the concept of modularity. All of the BCM flat top uppers feature a USGI type laser etched T-marks to provide addressing for the remounting of tactical accessories such as optics, laser sights, etc. This enables the weapon platform to be easily configured and then accurately reconfigured for each specific mission.
USGI 1/7 Twist Rate
The USGI 1/7 twist rate of all of the BCM barrels is the preferred twist rate by most professional infantryman. This twist rate has proven very versatile and can effectively run the new heavier 5.56 ammo that is hugely popular with military and private security personal for its’ superior ballistics.
Mil-Spec 4150 - Barrel Steel
BCM barrel steel is Mil-Spec per MIL-B-11595E. The 4150 grade (CMV) of steel is a Mil-Spec steel used in the USGI M16 family of rifles; it is stronger and will last longer than the typical barrels offered in the commercial market. The Mil-Spec grade 4150 gets its’ additional strength and rigidity from an increase in carbon and/or vanadium in the alloy. This will offer increased barrel life and performance through use in all types of extreme environments and temperatures.
Chrome Bore and Chamber
One of the first modifications that were made to the original M16 in the mid 1960’s was the addition of the chrome lined bore and chamber. It is now a world wide standard in the industry for a battle rifle. The chrome bore and chamber is harder than the barrel steel and on the USGI M16/M4 rifles will aid in chambering, extraction, and reliability. It increases velocity, and also resist against fouling and corrosion from extended use in the field. This gives the end user a longer barrel life with less required time in maintenance and cleaning.
Manganese Phosphate Barrel Finish
Barrels are parkerized with the manganese phosphate finish (Mil-Spec A-A-59267). Military specifications also state that the entire barrel surface is phosphate finished to create a porous surface to absorb oil as to resist against corrosion from the elements. BCM barrels are phosphated before installation of front sights. This is a much more extensive assembly operation, but insures that the entire barrel is finished and protected . . .even under the front sight base.
5.56 NATO Chambers
The USGI 5.56 NATO chamber is the best choice for effective deployment, reliability, and compatibility, of higher chamber pressures of military ammo.
Mil-Spec F-Marked Forged Front Sight Bases
Mil-Spec for rifles issued to the troops require taller front sight bases on all flat top AR rifles. Many commercial offerings use M16A2 height front sight bases on all of their barrels regardless of what type of upper it is installed on. As a result, owners of rifles and carbines with the flat top receiver configuration can have problems getting a proper ‘zero’ for elevation with Mil-Spec back up iron sights. As all of the BCM uppers are built for flat top uppers, all have the proper Mil-Spec F marked front sight base to insure the correct height for iron sight zeroing when using military iron sights. Mil-Spec taper pins secure the forged front sight base with the sling swivel secured by tubular rivets.
Government Barrel Profiles
Duty rifles are built to be carried - day in and day out. The USGI barrel profiles (often referred to as the Government Profile) enable the operator to carry their weapon for longer periods of time and deploy them faster than the heavier commercial H-Barrel counterparts. The government profile barrel is also compatible with the current M203 mounting systems.
HPT / MP Inspected Barrels
Military specifications require that barrels undergo a HPT (High-Pressure Test) load as a part of quality assurance procedures. Commonly referred to as a proof load, the M197 HPT is rated for 70,000 psi. BCM barrels are proof loaded and then MPI (Magnetic Particle Inspected) to detect any possible flaws in the barrels surface. The barrels are MP inspected with both circular and longitudinal magnetic fields per ASTME1444-01 (current Mil-Spec) to assure a high quality finished product. All BCM barrels are marked HP MP as our proof load marking.
Copyright © 2005 Bravo Company MFG, Inc.
Any ETA on the Midlenth’s?
From a personal POV, i have two (soon to be three) BCM uppers, and they are terrific units.
They are far and above the others in execution and quality.
If you need an upper- these are the ones to buy.
Hi Hawkeye,
In production right now are 11.5" and 14.5" and some 16" M4 are at chrome.
We are waiting on the M4 barrel extentions, and they are starting to come in.
Best estimate I can offer is 8-10 weeks.
Thanks,
Paul
Hi Pat,
Thank you very much for your feedback.
It is much appreciated 
Paul
BCo.
Paul:
I have five of your new uppers that I got from Grant and they are OUTSTANDING in every way. Great work getting those set up. Grant was kind enough to install Larue rails and SureFire Suppressor Adapters on them for me, and they accomplish any task given them thus far. Several of them are in use as student loaner guns.
The accuracy has been exceptional with the combo of a S&B Short Dot and Hornady 75GR NATO TAP. The new 75 GR Training Round from Hornady has performed to the same standard.
Thanks for the quality product.
Stay safe.
Ben
I just purchased my first BCM upper last night because I’ve heard so many great things about them and I can’t wait until it gets delivered.
Paul, the uppers look great, any other calibers going to be offered in the future? Keep up the great work!
Speaking of BCM uppers with Short Dots 
The 11.5" continued to impress me everytime I pulled the trigger. I’ve got some video that I can post if Paul wants… And, please guys, no critiquing my lack of ninja skills, or my lack of girth
Paul, Out of curiousity, which is lighter, the midddy or 16 m4? I was wondering if you had a middy/Larue 9 vs. a 16 m4 and Larue 7 or RAS if they would weigh the same?
Mark
CapnCrunch WOW
What rail are you using? And what is the length?
I hope to have an SBR like yours one day:)
Do you MPI each and every barrel or just one out of a batch?
Regardless, I have one on the way. After much research, this is the perfect upper for me and for future builds.
Stripped Barrels
Using my postal scale,
16" M4 Profile BCM barrel is 1lb-11.9oz
16" Mid Length, Gov Profile BCM barrel is 1lb-11.6oz
.3oz difference between the two barrels
That difference is so small, that I think only a scale could really notice the difference. So in practical terms, they are the same weight (before the additon of specific handguards).
Thanks!
CC - thanks for posting the pics!
We asked Capco to independently test a couple of the BCM 11.5" preproduction models.
HPT and MPI - 100% of every batch.
The HPT (High pressure test - often called proof loading) is the first part of the mil-spec “MP” quality assurance program. Every BCM barrel is proof loaded.
Then the MPI (Magnetic Partical Inspection) is performed to locate any cracks or abnormalities in the surface of the barrel. Every BCM barrel is MPI. The MPI is done by an independent NDT (non destructive testing) facility per ASTME1444-01.
Thanks!
Paul
BCM
Thanks much!
I would like to, but not in the near future.
It’s all I can do to keep up as it is now.
Paul
BCo.
That’s a big plus one, thumbs up! Thanks!
So, it would just be the difference in the rail system, the Samson rail must be heavier than the Larue, wonder what that difference is?
FOund it, Samson, 13.5, Larue 12.8 DD 11, so I would be 2.8 oz’s lighter with a DD and middy vs the Samson.
I may try a middy soon with a Larue.
Mark
Better be careful about that…I’ve heard things about this guy.