This particular question has probably has been asked & answered multiple times already, but try as I may, I can't seem to find it.
>>> What’s More Reliable in an AR15, semi-automatic / SBR, a 10.5" -or- 11.5" barrel ?? <<< Based upon the premise that ALL COMPONENTS BEING EQUAL, would an 11.5" barrel offer any greater reliability than a 10.5" barreled AR15-SBR ? Does that additional 1" of barrel really make a difference in the weapon’s functioning, or would the slightly shorter tube offer the same reliability ? As always, ANY & ALL replies will be very much appreciated. THANK YOU
The search function has a lot of problems. I use google and type in the following:
site:m4carbine.net
Then I type in my search query:
site:m4carbine.net best sbr barrel length 11.5"
one of those links in the search will yield a quote from Paul @ Bravocompany
“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.
It’s somewhat of a faulty question as there are a lot of quality vendors who make, can make, and will continue to make 10" guns run without issue in a variety of scenarios including suppressed & unsuppressed, heavier buffers, lighter buffers, etc.
For every inch you add back on an SBR, you tend to get better reliability, but if a 10" gun runs, it typically runs and comparing 100% reliable to another 100% reliable gun doesn’t tell us much, now does it?
LMT made those specifically to use with the project and they have always been successful.
Colt ran a bad rep with their’s, so they bumped it up to the 11.5, but there are so many companies going even smaller that it seems that you have a lot more choices than just those two.
My LMT SBR runs great along with two department owned LMT 10.5" SBR’s. My next SBR, in the works, will be a BCM 11.5". Paul said it best above the increased dwell time will help with reliability.
You might also consider BCM’s 11.5" uppers are on sale you can pick up an upper for $385 vs $485 for an LMT
so long as the port is proper I doubt many in this forum would ever see the benefits.
My 10.3 and .5 have never skipped a beat, there are gains to be had, but any (decent) barrel with the proper port and buffer pairing should be good to go.
With quality parts and set up properly I am willing to bet there will be no difference… Except for the internet commandos who “herd” differently. My 10.5" runs great.