BCM 5.56 Mid length upper (lightweight or std gov profile)


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jad0110
January 1, 2011, 02:50 PM
Hello all.

I put together my first AR from a rifle kit a few years ago. I did not want to spend a ton on my first rifle, as my experience with handguns told me the first one usually just gets you pointed in the right direction and you trade up soon thereafter.

My AR is built on a Doublestar lower, with RRA 2-stage trigger group. I have a 6 position CAR C4 stock and Del-Ton mid length flattop upper in 5.56 with a 1x9 HBAR (chrome lined). Yesterday, the gas key came unstaked. I got it temporarily restaked so that I can rule out any problems with the gas system before proceeding further (the bolt was cycling fully). From what I've read, older DTI Bolt Carrier Groups weren't necessarily the best quality BCGs on the planet.

At this point, at a minimum I'll swap out the entire Bolt Carrier Group for a unit from Bravo Co Mfg (checking headspace when I do so). I love the mid length design, it just makes a great all around carbine for me. But at the time I bought it, mid length upper selection was very limited. In fact, all the ones I could find were 1x9 twist with HBARs. IMHO, a HBAR on a 16 carbine with a light adjustable stock is a bit muzzle heavy for my tastes, and I'd like to have the option of shooting a variety of loads over 69 grains (such as Hornady TAP) as a bonus (1x7 twist).

Therefore, I am considering getting new flattop upper assembly and BCG from Bravo Co or Spikes Tacticle (5.56, 1x7 twist). Since I know I like the middies, I may as well go with one of the best. Two versions are offered, one with a pencil barrel (.625FSB) and one with a std government profile (.700 or so, I assume???).

I don't hunt with it, nor do I do a tremendous amount of rapid fire, maybe a single 20 or 30 round mag emptied into a bunch of water bottles, spoiled fruit and my kid's busted toys every now and then for craps and giggles :D. Mainly, the gun is for range fun/target shooting/SHTF/home defense backup to my Mossberg 590A. One day, it may also become my wife's primary HD gun when I'm away on travel (she finds my current HBAR middy muzzle heavy as well). I don't mind some forward weight to stabilize the gun a bit when shooting offhand, but I certainly want nimbler handling qualities than my current HBAR setup.

So given the above, which would you go with? Is there a noticeable difference in balance between a full pencil barrel and the std gov profile in a 16" carbine?

Thank you so much for your input.

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rust collector
January 1, 2011, 03:15 PM
I've got a RRA varmint AR, but the stainless bull barrel 10 pounder isn't a lot of fun to shlep very far. I used a chrome lined midlength slim profile upper for my next build, and it made a handy package.

Govt contour is better for multiple mag dumps or attaching a launcher, but slim profile has better balance and carries easier.

wnycollector
January 1, 2011, 04:08 PM
I have a BCM 14.5 middy with their standard profile barrel and permanently attached FSC556. On a cav arms poly lower is super light (6lbs with loaded 20 round mag and DD1.5 rear sight). I love this upper. I think the weight difference between their lightweight and standard profile is only 3-4oz.

briansmithwins
January 1, 2011, 04:30 PM
I'd go light. It makes the rifle handle SO much better.

It's not like you're going to be doing full auto multiple Beta mag dumps thru it.

BSW

jad0110
January 1, 2011, 04:42 PM
Thank you for all the replies.

To clarify further, I don't mind weight. Heck, I'm carrying a 4" S&W Model 28 Hwy Patrolman IWB as I type this. I just don't care for the muzzle heft of my current HBAR 16" middy.

RockyMtnTactical
January 1, 2011, 07:28 PM
Don't know how you can go wrong. I like my guns light though.

Mot45acp
January 1, 2011, 08:57 PM
I went with light weight mid-length from BCM I couldnt be happier. My reason for doing so was I didnt plan on mounting a M203 and it balances perfectly at the front of the mag well while using a Spikes heavy buffer and CTR.

It gets hot quick, but it cools down quick as well. I am very happy with my choice.

countryrebel
January 1, 2011, 09:01 PM
For the purposes you stated I would go with a lightweight barrel. Just my 2 cents.

Quentin
January 1, 2011, 09:35 PM
I recently ordered a Daniel Defense 16" LW midlength upper. Haven't received it yet so can't speak first hand but figured going with the 16" LW probably would weigh about the same as the govt profile 14.5" middy yet give the advantage of a removable flash hider and a little more velocity and sight radius.

I was torn between the same choices as you in the 16" profiles and mainly went pencil due to the ArmaLite HBAR middy I now have. I wanted to go much lighter than that and don't believe the pencil barrel will be a problem otherwise.

The govt profile has always confused me. I know it might heat up slower and resist bending a little more but it seems to me that extra weight out front is in exactly the wrong place, it should be .750" under the handguards and neck down to .625" after the gas block, not the other way. Seems like there'd be more chance of flexing at the thin section under the handguard so I went .625" all the way.

Z-Michigan
January 1, 2011, 10:22 PM
The govt profile has always confused me. I know it might heat up slower and resist bending a little more but it seems to me that extra weight out front is in exactly the wrong place, it should be .750" under the handguards and neck down to .625" after the gas block, not the other way. Seems like there'd be more chance of flexing at the thin section under the handguard so I went .625" all the way.

My understanding is that the "govt profile" was created for the M16A2 as a result of soliders bending the barrels of M16A1 rifles while using them for prying. Hence the heavy profile past the FSB and handguards; prying force would typically be exerted on the handguards and transferred to the barrel at the .75" gas block junction.

This could be wrong and I'd welcome any more detailed or accurate information others may have.

jad0110
January 1, 2011, 10:25 PM
The govt profile has always confused me. I know it might heat up slower and resist bending a little more but it seems to me that extra weight out front is in exactly the wrong place, it should be .750" under the handguards and neck down to .625" after the gas block, not the other way. Seems like there'd be more chance of flexing at the thin section under the handguard so I went .625" all the way.

I was actually wondering the same thing. As you said, makes no sense.

In any event, I figured, why not ... I went ahead and ordered the BCM 5.56 lightweight mid length with headspaced BCG. I think I'm going to like the feel of my carbine a lot more without the clunky HBAR.

I do have a potential buyer lined up for my existing upper. What do you guys think would be a fair price for a 16" Del-Ton mid length HBAR 1x9 5.56 flat top upper, chrome lined barrel with A1 front sight post/gas block and standard flash hider? It has about 400 rounds through it. Granted, a new gas key will probably have to be staked as the restake was just a temporary fix. Also, no rear sight assembly would be included, nor would it have handgaurds (I'm switching them over to the new BCM upper). $250 or so?

Thank you again for your assistance!

Z-Michigan
January 1, 2011, 10:26 PM
To the OP: it's not going to matter much either way, and the difference is only 3-4 ounces. I have a couple "govt profile" midlength rifles and have handled the "lightweight" .625" profile. The lightweight is a little lighter and better balanced, BUT the 16" middy govt profile is already nice and light and well balanced, as long as you stick to the plastic handguards. Add most rail systems and you'll be wanting to shed weight anywhere you can.

I think it's important to note that what is called "lightweight" on the AR would be a standard contour on almost anything else. Standard AKM and FAL barrels, and even the front portion of a M1A barrel (all of these are .30 cal guns with a larger bore, hence even less barrel wall thickness) are smaller diameter than the .75" front section of a "govt profile" AR barrel.

On the flip side, the AR can be a very accurate gun, but if you get the "lightweight" with standard handguards there is some potential for barrel deflection when changing positions or using/not using a sling. I don't have any numbers on how significant this would be in terms of accuracy. Probably less than a MOA, but I'm only guessing.

If you're going to stick with plastic handguards, personally I would choose the "govt profile" but it really won't matter much. If you're getting a rail system, I would definitely get the lightweight.

DAdams
January 1, 2011, 11:43 PM
Just did my first AR. 14.5 mid length. Did alot of reasearch, and didn't want to do a from scratch parts build. BCM, Spikes, and a couple others seemed to get the best reviews. Spent a bit more than planned but that didn't really come as a surprise as things evolved as to the quality and types of components appealed.

I bought the BCM Upper and Lower.

http://i100.photobucket.com/albums/m22/dadams111/BCM-UH-EAG1-2.jpg

http://i100.photobucket.com/albums/m22/dadams111/BCMLEFT.jpg

jad0110
January 2, 2011, 01:01 AM
Hey DA, so you did get around to building that AR? Pictures???

I guess my research wasn't quite as detailed. If I'd known everything I know now when I first put this rifle together, I would have at least staked the darn gas key with a punch, or I would have acquired a better BCG from Colt, LMT, etc.

Add most rail systems and you'll be wanting to shed weight anywhere you can.

That won't be an issue. I've yet to handle a rail system or free float handgaurds that felt as natural or comfortable as the plain-jane A2 style handgaurds.

JDMorris
January 2, 2011, 01:13 AM
Heavy barrel ;)

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