I noticed on the BCM website that there is an advisory for these barrels; full-power ammo is recommended, apparently for reliable functioning. The advisory says to use an H buffer; carbine buffer recommended for lighter loads. This makes me wonder if there might be an issue due to the shorter length of barrel in front of the FSB on the 14.5 middys. It’s probably a non-issue (website says the 14.5 mid setup is ‘specifically tuned’, presumably to avoid any issues) but I am curious about it nevertheless and would like to hear from users on any issues thusfar. Still trying to decide on a middy upper, definitely going BCM but will it be the 14.5/perm A2X, or a 16 LW or standard. Thanks in advance! 
I have exactly one mag through this setup, and it was 28 rounds of Black Hills 75 grain blue box. It ran like a champ, with almost no muzzle rise, for all 28 rounds.
I’m going to try it with Wolf 62 grain and see what happens, and play with the buffers as well.
I’m gonna run some federal xm193 through mine this weekend.
And also some PMC 55gr. which is known to be light powered.
Will post results sat night.
I’ve got a CMMG LW 14.5" Middy and I haven’t had a single problem in the 500 rounds I’ve put through it. I’m using an H buffer and a semi-auto carrier with a BCM bolt upgrade.
So far I’ve put Wolf, Old Norinco chi-com crap,Remington UMC, Win 3131, Black Hills 77gr, and M855 through it without a single hiccup.
My bud Skinja has one of these and I only fired 20 rounds of XM193 through it - side by side with my N4 Recce and the lack of recoil impulse on the BCM was very noticeable compared to my 16" mid length. Very impressive. Not sure what other ammo he’s tried in it yet however.
I’m not sure this is a 1:1. I would bet that the CMMG has a larger gas port than the BCM, and if it ran Wolf I would bet that’s the case.
I have 2200 rounds through mine including 1500 over a 3 day carbine course. All ammo was Centurion M193 brass cased 55gr except for a few federal 69gr rounds I had. No problems. My buffer isn’t marked as an H buffer. I might be an “H,” but at this point I can’t even remember where it came from.
And, I will add, this setup is fantastic. It is light, fast and has the recoil of a mouse fart. 
Was doing some chronographing through my BCM 14.5" mid a couple weeks ago, this is a new rig with only perhaps 75 rounds through it at the time. I can say it was functioning just fine with a mag full of Hornady 55 gr. TAP. This stuff was clocking a measly 2650 fps, while both the Federal xm193 and IMI 193 were running a good 350 fps faster.
I sheepishly admit I don’t know what buffer is in the lower, it’s a full S&W lower purchased from G&R, for what that’s worth.
I will say that this rig shot noticeably smoother than my stock Colt 6920. Great upper.
Dan
I wouldn’t doubt it at all. What would be the benefit of BCM using a smaller gas port? I know they know their shit, so there’s probably a good reason.
hey- i have run 500 rds thru mine, 14.5mid ddfspm,s/f f.h., have run xm193,77grn b.h.,62grn ss109, 52grn fed and wolf 55 an 62 grn junk,EVERYTHING WORKs!! i run a lmt factory lower with a standard car buffer was going to put in a H but don’t really see the need, i run a lwrc m6a2 stretch with same results[h2 buff] but for the money the 14.5bcm is the best carbine i have run in over 20years behind a rifle, when i can swing it i will build #2 and have some identical goodness,also as JHC[joe] says there is NO muzzle flip[rise] and i am using a standard surefire flash hider,really great ,lite ,fighting rifle.thanks for listening,T sure if you ask joe will post some pics of my build for ideas
I only have 570 rounds through my BCM 14.5" mid-length upper so far, 150 of those rounds were fired with my surefire suppressor attached, and I haven’t had a single issue.
Ammo used was 370 rounds of Hornady 55gr Training ammo, and 200 rounds of PMC 55gr.
Thing is, I just now went and checked to see what weight buffer I had in there because I couldn’t remember right off hand, and this ENTIRE time I’ve been using an H2 buffer by mistake. I thought it was a carbine or H1 this whole time:p Guess I’ll just go ahead and keep it in there for now.
Anyhow, this upper is one smooth shooting bitch, that’s for sure.
Suppressed an H2 will be fine on a 14.5" BCM midlength. Mine will run with a H3 suppressed.
Yeah I know, I was mainly talking about the other rounds I fired unsuppressed. All in all, I’m really digging this carbine!
Smaller gas port equals less recoil and less wear on the gun.
C4
That’ll be a good test. That Bronze is about the weakest factory ammo you can get.
Interested to see if it runs wolf OK.
I’ll buy when they get a 14.5 LW middy out. Considering they can’t keep the regular LW middy in stock, I’ll hold my breath at my own peril.
That’ll be a good test. That Bronze is about the weakest factory ammo you can get.[/QUOTE]
My BCM 14.5" optimized gas system gun runs just fine on PMC. I’m using a CMT H buffer, LMT enhanced carrier with a BCM carrier key, BCM bolt, cam pin and firing pin and with PMC it locks back every time. With the AAC Brakeout it shoots very soft with very little muzzle rise.
The next ammo I need to try is Wolf, Remington/UMC and Radway Green.
Can somebody give me some gas port sizes for a 14,5 midlength barrel. So we can compare the different brands
14.5" middy barrel gas ports can be anywhere as there is no set standard.
Companies like BCM and Noveske are typically going to use smaller GP’s.
C4
What range are we talking here ?
Smallest to largest?