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BCM 20″ Government Barrel: Raw Truth Review

This review has been a long time coming. I kept putting it off because I honestly wasn’t sure where I wanted to take it. The BCM 20” government upper is another quality assembled upper receiver, and I didn’t think that would be all that interesting to write about.

But it’s worth writing because it’s not really just about the upper and barrel. What I find the most interesting about this upper is what it represents.

You see, these days, a full length 20” upper seems downright antiquated on the internet. Just about everyone has settled on 16” carbines or going even shorter if they want to play the NFA game or build a pistol. The 20”, in comparison, seems like a dinosaur from the early days of the AR-15 and M16.

This article contains affiliate links.

In this review, I’m going to wax poetic about the 20” barrel just as much as I’m going to go over BCM’s product itself.

Let’s get to it.

Bottom Line Up Front

Let’s get this out of the way, first. I picked this upper up with my own cash in 2014 from Bravo Company USA. The BCM 20” government upper and barrel is a quality piece of hardware that will certainly scratch that “retro” itch you might be feeling. It shoots accurate enough and has never malfunctioned on me no matter what I’ve fed it.

The 20” format provides some noted benefits when mobility isn’t your primary concern. It produces great velocity, nice forward balance for marksmanship, and the rifle length gas system reduces the felt recoil impulse to a mere push.

Combine it with a collapsible stock and it’s actually a very handy weapon that I’ve used in everything from tactical training courses to shooting matches between 5 and 500 yards.

M16A5 configuration using BCM 20" government upper
My M16A5 configuration using a BCM 20" Government Profile Barrel

Yes, it is slower handle and maneuver than something shorter and lighter. If speed is your priority, then this probably isn’t the path for you.

In all, the BCM 20” rifle is a favorite in my safe, and it accompanies me on more range trips than any of the others. 

But I also know it’s not the most practical.

So Why Get a 20” Barrel?

I might as well talk about why I picked up a 20” barrel to begin with.

Let’s rewind the clock back to January of 2014. I had just started The Everyday Marksman as a way to document my shooting journey. At the time, I already owned two ARs, the Recce and the MCC.

The same month I started the blog, a good friend of mine suggested that we sign up for Vandenberg Air Force Base’s  Excellence in Competition (EIC) match. It was taking place just a few months later in March.

The EIC match follows standard positional rifle match rules with iron sights and off-the-rack M16A2 rifles.

I signed up and bought a BCM carry handle to start working on my iron sight game. Those practice sessions made up the earliest blog posts on the old site.

Unfortunately, I ended up missing the match due to scheduling conflicts (I competed in it two years later, and won a medal). 

I was bitten by the iron sight bug and wanted more. Knowing that I wanted to prepare for the next match, I purchased the BCM 20” Government complete upper in May of 2014 and slapped the carry handle on the rear. I took that to an Appleseed event started preaching the gospel of irons.

And that gets me to the first benefit:

BCM 20" government
When I first purcahsed the BCM 20" Upper, I slapped on some plastic MOE handgaurds, a carry handle sight, and away I went to train

Sight Radius

It’s not something most people think about in the age of “optics on all the things,” but the longer distance between the rear sight and front sight post on a rifle-length barrel is a precision advantage.

This is true for a few reasons:

  • Since it’s farther away, the front sight appears narrower and more precise
  • The adjustment wheel bullet drop settings on a carry handle sight are calibrated for a 20” sight radius
  • The increased distance improves your depth of field, meaning that the target is less blurry when you focus on the front sight

I don’t want to go into the mechanics of the elevation wheel here since I already did a thorough write-up on that topic.

To the third point, Lothaen at The New Rifleman did a great job detailing the depth of field improvements with rifle-length sights.


In the world of small caliber high-velocity (SCHV) cartridges, like the 5.56, velocity is king. The simple truth here is that a 20” barrel is the optimum length for 5.56-based cartridges. The whole system was built and balanced around a 20” barrel.

Yes, engineering developments have brought us some very capable bullet designs that work well from 16”, 14.5”, and shorter barrel lengths within a given range envelope, but the 20” will still do it better.

BCM 20" government barreled upper
Another angle of the original configuration I had for the BCM 20" Upper on my Recce's lower

This is particularly applicable to the 55gr M193 cartridge originally designed for the M16. That round absolutely requires velocity for effective performance. Some of the devastating wounds generated in the early experimental fielding of the M16 stemmed from the combination of 55gr and high velocity.

This works to our advantage because buying bulk M193 is pretty cheap compared to heavyweight 69 and 77-grain ammunition. So, if you want to buy a lot of 55gr stuff and have it work effectively, a 20” barrel is the way to go.


Granted, this is geared more towards a marksmanship-oriented audience, but a 20” barrel helps with rifle weight and balance. The extra length provides “hang” and helps stabilize the rifle in the hand. This is great for positional shooting.

That said, the same hang that provides stability for shooting from the kneeling also slows the rifle down when you move from target to target.

The Bravo Company USA 20” Government Profile Barrel

When I ordered the complete upper from BCM in May of 2014, I honestly didn’t know what to expect. Everything on the internet told me that such a dinosaur would be unwieldy, heavy, and just a bad shooting experience.

They were all wrong.

The upper came in the classic BCM brown box. As expected, it was cleanly assembled with no tooling marks or anything of the sort. The fit of the upper into all of my lowers is nice and tight, though that’s something I’ve never particularly worried about.

I think the first thing that stood out to me was that a 20” barrel really isn’t that much longer than a 16” barrel. Sure, four inches is four inches, but the internet would have you believe it would feel like you were waving a 2×4 around. It’s simply not

Just a quick comparison of a 20" barrel against a 16" one. The difference really isn't that much

Combined with a collapsible stock, as I do, it remains a fairly handy package with all of the benefits of the longer barrel.

Don’t get me wrong, though. Compared to my lightweight barrels, you can definitely feel the extra mass up front. That’s the nature of the government profile. However, just because it’s longer doesn’t mean it has to feel like this. For example, I don’t notice the length nearly as much on something like my 18” Faxon Gunner Barrel, which is almost as long but without the extra mass.

Accuracy of the BCM 20”

Of course, it wouldn’t be a barrel review without speaking to accuracy.

To be honest, I’ve never done a formal evaluation of the thing. But I did use this upper almost exclusively for three years in my marksmanship training. I’ve configured it in every which way from a iron-sight KISS rifle up through a designated marksman rifle.

Given a good quality of ammo, I would expect about 1 to 1.5 MOA out of the barrel.

The best group I ever shot with it was with ADI 69gr Outback, which came in just about 1 MOA at 100 yards with a 4x optic. Now, could the barrel have done better than that? Maybe. I was just shooting in from the prone position off of a pack, so there is always room to lock it into a rest and test it again. I just never felt the need.

Five shots at 100 yards with a 4x optic and 69gr ADI Outback


I would be lying if I said that the BCM 20” barrel handles just as well as one of my shorter and lighter models. It doesn’t. But it doesn’t handle poorly, either.

When I was running around the jungle lanes with it in MVT’s HEAT 1 class, I never felt like it was unwieldy or awkward. In fact, the slight forward balance caused it to be very stable during strings of fire, which actually inspired confidence in it.

That said, the forward balance does slow it down as you transition quickly from target to target.

When I used this upper during an NRA ARC match, it kept up just fine with the guys running shorter barrels, and I even turned in some great times on the CQB stages that beat everyone else in my squad. Though I probably would have done even better with something shorter and lighter, it was still respectable.

Let’s be real here, though. I’m not saying it handles wonderfully. There is a distinct forward balance, especially if you use a lightweight collapsible stock. I ended up mounting a UBR 2.0 to counter the weight, which brings the balance point to the front of the magazine well. In all, the total weight of this rifle with optic and no magazine is 9.4 lbs.

“The Feel”

If you’ve never had the pleasure to shoot at 20” barrel with rifle gas system, you really need to give it a try. It’s really one of the simple pleasures of the AR world. Everyone who I’ve handed this rifle to has commented on just how smooth it is to fire, and immediately ones to build one of their own.

It’s very hard to describe, but saying that the recoil impulse of the BCM 20” is mild would be an understatement. It really is just a gentle push against the shoulder and makes for a fantastic experience for new shooters.


If you can’t tell, I’m a big fan of the BCM 20” barrel and upper. I don’t think 20” uppers deserve nearly the negative reputation that forum fanboys gave them. In fact, I think that perception was starting to change for a while, as I kept seeing more and more 20” build threads in the message boards.

However, I’m going to stop short of saying that this is really the only upper you need.

You see, a 20” barrel has a lot of advantages under very specific circumstances. But a lot of those circumstances do not apply to many shooters. For example, the long sight radius becomes a moot point once you mount optics. The increased velocity doesn’t matter nearly as much when your primary use is inside of 200 yards with modern ammunition.

The 20” barrel is devastating at closer ranges with 55gr M193, but not a lot of people are shooting that stuff anymore for “serious purposes.” If you’re already planning on using something like 75 or 77gr loads out of  16” barrel, which you should, then the 55gr velocity from a 20″ isn’t important to you.

Lastly, with ounces being as important as they are, folks who put a priority on building the lightest rifles possible simply aren’t going to do that with a 20” barrel. Could I get this rifle lighter than the 9.4 lbs it weighs in at? Sure, if I stripped a lot of parts off of it and went with lightweight options I could probably drop that by a pound.

But that’s fine.

You see, not every rifle has to have a purpose. Sometimes we just want to build and shoot something because we like it. Out of my entire collection, nothing is a pleasant and as grin-inducing as the BCM 20”, and I think that says something.

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Matt is the primary author and owner of The Everyday Marksman. He's a former military officer turned professional tech sector trainer. He's a lifelong learner, passionate outdoorsman, and steadfast supporter of firearms culture.

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Oldest First
Newest First
Ilya Koshkin

Very nicely written. I will add that you can get a soft recoil impulse by combining a mid-length gas system on a 16″ barrel with a rifle length extension. That is one of the reasons I use the Ace UL stock on ARs where I do not need to have someone short use it. The only other comment I’ll make is that lightweight 18″ and 20″ barrels do not get the credit they deserve. Most of my ARs are either 16″ or 18″, but that is mostly a matter of me experimenting. My AR-10 has a 20 inch barrel. I… Read more »

Ilya Koshkin
Replying to  The Marksman

A can makes a difference, that’s for sure. I do not like large frame ARs too much since the increased bulk does not do anything for me and they are harder to shoot. Too much mass is moving around, so with a lightweight AR-10 you have to hold onto to it for dear life. I originally built mine with a light 18″ 308Win barrel, but after some time with it, took everything apart and rebuilt it around a heavy 20″ 243Win barrel. This is sort of my varminter and in this configuration it is a much better platform. Instead of… Read more »

Sunshine Shooter
Replying to  The Marksman

Can you elaborate on the A5 kit you mentioned?

Sunshine Shooter
Replying to  The Marksman

So does it only fit certain stocks?


Dumb question probably but can you just slap a 20 inch upper on a carbine lower (i.e. one with a collapsible butt stock, carbine H buffer, spring, etc.) and count on it to run reliably?


Yes, finally /joking! Thanks for putting this together. There was a lot of good info here that people looking at this upper can use. I’ve got my MCC setup locked in. My next purchase goal is a 20” set up and this in part helped me land on the BCM option over PSA and Aero. I want to own an example of the type for recreational purposes, to dip my toe into local CMP/High Power matches, to run in it some 2 gun matches, and classes. I know it’s not ideal for some applications like CMP/HP. But I’m taking a… Read more »

Replying to  The Marksman

Exceptional write up of the much anticipated BCM 20 inch Gov’t Upper. Of note: Took my youngest out to dial in and shoot his PA 1-6 ACSS optic last week and his first comment after putting 120 rounds of 62 grain M855 and 69 grain SMK down range was how impressive the lack of heavy recoil experienced out of his 20 inch BCM upper. Quite a contrast as his few annual range trips with dad are generally spent firing away with a Norinco MAC 90. 55 grain shooters. If you are reloading, the Hornady 55 grain FMJ Item # 003-2267… Read more »

Regular dude
Regular dude
Replying to  The Marksman

Nice build, looks great, and I do commend you and The New Rifleman for dedicating time to put out posts that show the how and why of rifle marksmanship. Picked up a new perspective and appreciation for the 20″. Regarding the rail, is this Daniel Defense’s drop in + free float? Looks like a good option for someone who cut their teeth learning the fundamentals on MOE’s or USGI handguards, and now want the option to free float their AR without tearing apart their upper. Also, about the rail panels on the Omega, how do you like the Magpul XTM’s?… Read more »

Colorado Pete
Colorado Pete

My first foray into AR’s was a Colt H-Bar Sporter upper on a collapsible stock. We used the same at work until recently (they just went to 16″ standard-weight uppers). Very front-heavy but easy to shoot. Funny, when I was a youngster, 20″ was considered a carbine. 22″ was standard round hunting rifle length and 24″ for magnums. The M14 had I think a 22″ barrel and the M1 of course was 24″. The 20″ Winchester 94 was officially designated the carbine while the “rifle” version was 24″. Of course that was back in the “stone age”. Times, and perspectives,… Read more »


My second AR build is something of an A4 semi-clone: incorrect muzzle device, non-standard lower receiver decor and M4 feed ramps, but otherwise a full-up, non-free float 20-inch rifle with the much maligned A2 stock. It’s also a 9lb beast! While it’s completely impractical for some applications, it has seen more range time than all my other ARs. I can’t imagine an AR collection/arsenal that doesn’t have a 20-inch in it. Despite the weight penalty, I find it has a reassuring heft. I’ve rung steel at 500 yards with it using my 4×32 ACOG. It is my favorite of the… Read more »

Replying to  The Marksman

Well, it would be less than honest to say that my A4 semi-clone wasn’t inspired by the original version of this blog. In fact, my 20-inch wore a UBG Gen 2.0 for a while, inspired by the look of your rifle. For wahtever reason, nostalgia or glutton for discomfort, I slapped the A2 stock back on, and put the UBR on my first build. The plan for my irons-only upper involves a free-float rail, an A2 upper receiver, a Faxon Gunner profile 20-inch, and gunsmithing work for a pinned FSB.

Al Anaday
Al Anaday

OK, a new-to-the-game question…
Why not buy a 20″ barrel and mount it to an existing upper rather than buy an entire new upper?
You could/would get the rifle length gas system as well?

Al Anaday
Al Anaday
Replying to  The Marksman

So the barrel and FSB/gas block bits are the least “standard” parts of the platform then, as far as interchangeability goes.

Great info as always. Thanks.


barrel length affects bullet velocity, military .556 ammo has to be above a specified velocity when it impacts a target and at the specified penetration depth will start to tumble to produce it’s designed wounding characteristics, outside those parameters it produces a wound channel consistent with bullet diameter. All that to properly state longer barrels give longer effective ranges. barrel length vs. accuracy (without environmental effects) no direct correlation – a lot of variables of internal ballistics come into play. A .308 rifle with a 13″ barrel can be more accurate than the same barrel at 20″ (with environmental effects)… Read more »

Replying to  Dale

As the article discussed barrel length I forgot to mention chamber cut and rifling twist rate also has effects accuracy


I am trying “vicariously” to assemble “on paper” a budget M16A4 clone and have decided on a free-floated 5.56 NATO chamber 20″ 1:9 twist HBAR chrome-lined Govt profile barrel that will be capable of 1 MOA with milsurp M193. it is great to know a fellow gun nut agrees that such a vicarious project makes perfect sense.

Replying to  Matt

Copy that. Thank you.

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