BCM: 14.5" Standard Carbine Gas Upper or 16" BFH Midlength Upper?

[CajunCourier]

I just finished assembling a new lower (LMT). I'm going to just buy a complete upper rather than building one. I've narrowed it down to a BCM 14.5" pinned and welded standard button cut barrel with carbine length gas (they don't make a carbine gas 14.5 in BFH), or a BCM 16" Mid with a CHF barrel. Which one would work better with .223 lower pressure ammo in cold or otherwise harsh conditions?

Which would you pick as a general purpose carbine, and why?

[Clint]

A 14.5 Midlength is a better configuration than the two listed.

[CajunCourier]

A 14.5 Midlength is a better configuration than the two listed.

Don't those have a history of needing full power 5.56 to be run consistently? What's better about it?

[Wake27]

Don't those have a history of needing full power 5.56 to be run consistently? What's better about it?

Those answers have already been answered 7 million times on this site.

[Clint]

14.5 MID is an Optimal gas system configuration.

Here is a nice article about some of the testing that was done recently to prove it.

https://www.m4carbine.net/showthread.php?206740-NSWC-testing-on-gas-systems-CARBINE-VS-MID-LENGTH


Don't those have a history of needing full power 5.56 to be run consistently? What's better about it?

[1168]

Its been very well covered on this site, but given an appropriately sized gas port, 14.5” mids cycle .223 just fine. Most barrels available seem to be ported with .223 in mind, even if they say 5.56 on the side. As Clint pointed out, midlength gas is optimal for 14.5” barrels. The carbine length gas system was originally spec’d for reasons that have nothing to do with reliability or durability.

[CajunCourier]

Got it. Well this certainly complicates my choices even more. :D

[RHINOWSO]

You are measuring with a micrometer here, either of the 3 uppers will work fine.

I have a 16" Mid BCM ELW and it is great.
I have a 14.5" Mid Noveske and it is great.
I have 16" Carbine Colt and it is great.

The more important question is do you ever see the need to change out of the muzzle device? While not impossible on a 14.5 pinned, it can be more difficult.

[1168]

Got it. Well this certainly complicates my choices even more. :D

To better understand your goals:
Is there a reason you are married to .223? Or perhaps there’s a particular load you have in mind?
Are you in Louisiana? How cold are we talking about?

[CajunCourier]

To better understand your goals:
Is there a reason you are married to .223? Or perhaps there’s a particular load you have in mind?
Are you in Louisiana? How cold are we talking about?

1. I'd say I'm pretty married to .223/5.56 in this rifle. I do plan on a .300 blk pistol w/ brace as my next AR, but for this one I want to be able to use my horde of PMC Bronze .223 for practice.

2. I am in Louisiana, but I frequently work up north during the winters. There are some carbine classes I'm planning on attending while I'm up there this year. If it's anything like last year, it's going to get pretty damn cold while I'm there (North Dakota and Minnesota), so I want it to be able to run reliably in those conditions.

[GH41]

Someone make be a believer in a small port gas port (less wear and tear) and a large port that will reliably shoot anything. Leads me back to why BCM only sells the A5 kit with the 0 buffer. Why expose yourself to the possibility of softer ammunition not working at the expense of longevity or recoil impulse?? While derailing the thread I want to ask one last question.... Why do you think a hammer forged barrel is better than one that isn't if both are chrome lined? In either when the chrome is gone both are worn out.

[bigshoe83]

Someone make be a believer in a small port gas port (less wear and tear) and a large port that will reliably shoot anything. Leads me back to why BCM only sells the A5 kit with the 0 buffer. Why expose yourself to the possibility of softer ammunition not working at the expense of longevity or recoil impulse?? While derailing the thread I want to ask one last question.... Why do you think a hammer forged barrel is better than one that isn't if both are chrome lined? In either when the chrome is gone both are worn out.

That’s a great question, following to hear responses.

[Sry0fcr]

Someone make be a believer in a small port gas port (less wear and tear) and a large port that will reliably shoot anything. Leads me back to why BCM only sells the A5 kit with the 0 buffer. Why expose yourself to the possibility of softer ammunition not working at the expense of longevity or recoil impulse?? While derailing the thread I want to ask one last question.... Why do you think a hammer forged barrel is better than one that isn't if both are chrome lined? In either when the chrome is gone both are worn out.

Trying to port a gun that works for steel cased Tula .223 all the way up to M855A1, suppressed and unsuppressed, from -70 up to 130 and have it recoil like a powderpuff is an impossible task. There ain't no free lunch here.

On hammer forged barrels, I don't think one is "better" and I don't think that the average shooter is likely to realize the primary advantage of a hammer forged barrel (i.e. longer life). Unless you're actually shooting out barrels, it's mostly a marketing gimmick. Kinda like all the Ford Raptors in my suburban neighborhood... If you're fielding a fleet of guns that expect to see high round counts and long service lives things like improved bolts, & hammer forged barrels make a lot of cents [see what I did there?].

[1168]

But you don’t have to slow down for speed bumps with a Raptor, amiright? (End sarcasm)

OP, I think you would be well served by the BCM 16” midlength you are looking at. Someone that shoots the notoriously light PMC Bronze you have may chime in, but it’ll probably be fine in Da Boot. I would bring proper 5.56 ammo if you wish to shoot in the frozen north, solely on speculation. Or, just test fire it while already dirty before you start a class, then clean and lube it. Throw a lighter buffer in if it won’t lock back. I’ve been shooting 13.7” to 14.5” middies in NC, SC, GA, and LA for a while with no issues, summer or winter. ~14” middies are pretty much my favorite configuration.

[CajunCourier]

I ordered the 14.5" pinned/welded BCM SOCOM upper with the carbine length gas system. Carbine gas is a known quantity to me and I know it'll run anything I put through it in any condition. I'll pick up a midlength later.

[1168]

I ordered the 14.5" pinned/welded BCM SOCOM upper with the carbine length gas system. Carbine gas is a known quantity to me and I know it'll run anything I put through it in any condition. I'll pick up a midlength later.

I’m fairly confident that, too, will serve your purposes just fine.

[magister]

I ordered the 14.5" pinned/welded BCM SOCOM upper with the carbine length gas system. Carbine gas is a known quantity to me and I know it'll run anything I put through it in any condition. I'll pick up a midlength later.

I have a 16” bcm carbine and 16” bcm midlength. It doesn’t normally get very cold in south Mississippi, but I can say that on one of our colder days a few years ago (17 degrees I believe it was) that both ran pmc bronze without issue. I’m sure your 14.5” will be just fine and so will a 16” midlength if you ever pick one up in the future.

[04rwon]

I have a few bcm’s. 16 mid, 14.5 bfh mid, 14.5 carbine, 11.5 carbine. By far my favorite is the 14.5 mid. The others are great, the 11.5 is becoming a close 2nd. Honestly very hard to choose the best but the 14.5 mid edges them all out for me. Its smooth, accurate, been reliable. Thats my go to ar. If i could only have 1, thatd be it.

Have had mine out in the maryland winters and florida summers. Few thousand rounds, cant remember, have had them for about 7 years. All has been good, any ammo, any weather.