Armory Sponsor
Posted: 3/12/2010 12:25:03 PM EDT
|
So I've read here if I'm going to build an 5.56mm SBR upper, I would be better off with an 11.5 over a 10.5? Then again, I see a lot of people (Some of them HSLD types) using 10.5" and shorter barrels so I'm thinking a 10.5 can't be that bad? Are the guys preaching 11.5" or longer making too much out of something relatively minor or uncommon or are the 10.5" guys in denial? (feel free to chime in on this one)
I have also read here that if I'm going to get a 10.5"-12.5", I may be better to having a 14.5" or 16" M4 barrel cut down (as opposed to buying a factory SBR barrel)? A. Because some short barrels have a heavier profile under the hand guards then a M4 does so a cutting down M4 barrel would be lighter then a factory barrel of the same length and B. So that I know the threads are done right and concentric with the bore and it will have a nice crown (assuming I send it to ADCO) which can prove to be very important if I plan to add a suppressor later yes? So OK then my real question is this, if I have a 14.5" M4 barrel cut down to 11.5", does anybody know exactly how much weight that will cut off? What about from 14.5" to 10.5"? |
|
I sold my 11.5" upper and got a 10.5" and my accuracy was considerably better with the 11.5"
and supposedly the 11.5" is the more reliable of the two. That said I love my 10.5" LMT As long as you read what profile barrel you're buying you should be good. The lmt has a govt. Profile barrel which is much lighter than a heavy barrelled cmmg |
|
Thanks for the input F_C...
Quoted:
The lmt has a govt. Profile barrel which is much lighter than a heavy barrelled cmmg The LMT was the one I was worried about, from what I've read and can tell in the pics, the LMT 10.5" is thicker under the handguards then a standard M4 barrel? I don' want to loose the weight advantage of going to a shorter barrel by having one with a heavier profile. Am I wrong about the LMT 10.5 having a thicker profile? |
|
Quoted:
Thanks for the input F_C... Quoted:
The lmt has a govt. Profile barrel which is much lighter than a heavy barrelled cmmg The LMT was the one I was worried about, from what I've read and can tell in the pics, the LMT 10.5" is thicker under the handguards then a standard M4 barrel? I don' want to loose the weight advantage of going to a shorter barrel by having one with a heavier profile. Am I wrong about the LMT 10.5 having a thicker profile? if i remember correctly they both have a government profile barrel, which is light contour (images grabbed from google, camera has a dead battery) 
|
|
They look similar but it's hard to tell for sure from a pic. the 10.5" looks a little fatter but that could just be the pic. I guess even if it is fatter, it's not by much.
Do you have any theory why your 11.5" was more accurate then the 10.5? Barrel length alone really shouldn't effect accuracy? |
|
honestly i don't know for sure
the opinions out there are that 11.5'' is more stable, and more reliable.. but i can't imagine why an inch matters for 2-3'' of accuracy. there might be some science behind it that someone more experienced in barrels and ballistics might know |
Accuracy has nothing to do with barrel length. Velocity does. Shorter the barrel, the greater the loss in velocity. My 11.5" has never missed a beat. My 10.5" is fine after the gas port was opened up. I run 9mm buffers and FA carriers in both. I'll warn you, if you get a 11.5" you will still want a 10.5"
|
|
Quoted:
Well I found a good pic of an LMT 10.5" barrel on the EE and from these pics it is clear to me that their 10.5" barrel is thicker under the handguard then a standard M4 barrel. http://i.imgur.com/kL1Jp.jpg http://i.imgur.com/dpqT0.jpg i assure you the profile maybe slightly thicker, but my upper is light as hell |
|
Quoted:
Quoted:
Well I found a good pic of an LMT 10.5" barrel on the EE and from these pics it is clear to me that their 10.5" barrel is thicker under the handguard then a standard M4 barrel. http://i.imgur.com/kL1Jp.jpg http://i.imgur.com/dpqT0.jpg i assure you the profile maybe slightly thicker, but my upper is light as hell Depending on how you have your's setup, I don't doubt that. Right now I'm trying to decide between going 10.5 vs 11.5 and which ever way I go (but specifically if I go 10.5), I need to decide between having my current M4 barrel cut down or just buying a 10.5" upper? Barrel weight\profile is not the only deciding factor but it does play into the decision because I want to keep the overall weight down as much as possible. |
|
Bravo Company has a nice little write up on why they chose the 11.5 over the 10.5
Q: Why BCM chose the 11.5" SBR over the 10.5"
I get this question a lot. It is a good one. When we spec our program we can build anything we would like, so we sat down and looked at the pros and cons. First Statement: I know a good 10.5" SBR can run very well. I personally own a semi MK18 type and it runs great. No problems. A: Dwell time. Dwell time is the time that your gas operated weapon maintains pressure to continue the cycling of the weapon. It primarily exsists from the time the bullet passes the gas port in the barrel to the time the bullet exits the muzzle. When you pull the trigger and fire the weapon the movement of the bolt carrier group unlocks the bolt, extracts, and ejects the spent casing. Then it cocks the weapon, feeds, chambers the next round, and then locks again. One of the thing that can make SBRs finicky is the dwell time (or lack of). The 11.5" carbine is approximately 4% longer weapon than its' 10.5" counterpart, but this extra inch gives the barrel a 40% increase in length for dwell time. IMHO, this is an excellent trade off. This additional dwell time (all other things being equal) will allow the carbine to be more forgiving to different ammo types, extremes in air temperature, weak or worn extractor springs, worn extractors, buffer weights, etc. Last Statement: For those folks who have a 10.5" that works very well, I would reply; me too. (see first statement) If I had to "go to war" with a AR15 Carbine, I would grab the BCM 11.5". The BCM 11.5" Runs Like a Dream. Hope this info helps, Paul Of course now they offer the 12.5 too... |
|
I had a 16" upper cut down to 10.5" & gas port opened at the same time. Works great suppressed or unsuppressed, even with Silver Bear ammo.
$79 return shipped (including disassembly of upper receiver) was well worth it to have a concentrically threaded barrel IMHO. It was also less of a beating I'd take than trying to sell the upper on the EE to buy a new one 
|
I like the YHM 10.5" Diamond Fluted barrel alot. I shoot mostly 45-62 grn projectiles, which it stabilizes fine. It is a 1x9 twist barrel if that matters to you.
Unfortunately I already have it installed, so I can't take a naked bbl picture for comparison. 
|
Armory Sponsor