Also a great alternative barrel to the M4 for your M4 6933 Commando build, or other SBR builds. 11.5" is actually the best length for an SBR with a carbine gas system. Cycles better than 10.3" or 10.5, but it is a little longer. You won't want this for a true Mk18 build, but not every SBR has to be a Mk18. Try pairing this barrel with a nice KAC RAS and good flash hider or suppressor. Suppressed fire works great with 11.5"
Gas port measured with pins at 0.070", and maybe a little under. Newer CAGE code marking "13629 MP 5.56 NATO 1/7" As you may know, Colt changed to CAGE codes on their barrels.
The heavy profile and is exactly a SOCOM profile, but does not have the M203 cuts. I have attached a picture with this barrel, without FSB, next to a Colt M4 SOCOM barrel. As best I can tell, the profiles are identical. I have measured the barrel before the gas block, and my calipers read 0.0845" on both barrels. I have had people tell me: 'now way the KAC M4 RAS fits on the FBI HBAR.' Well, if it fits on the SOCOM, which it does, then you are golden. Also great with the standard Colt Carbine hand-guards.
Weight with FSB is 33 oz.
Note on Colt 10.3" & 11.5" barrels: Charlie's offers a variety of choices for the collector, clone-builder, law enforcement officer and shooting enthusiast.
We take special care in bringing you the best in short barrels, and use the best artisans, both in-house, and in our extended supply chain, when something has to be engineered to a Colt production barrel. Our collectors and cloners will want the 10.3" barrel for historical accuracy. The Daniel Defense is a great option, as it is now being used by US Special Forces in limited numbers, and is readily available and affordable. For more authenticity, choose a Colt 10.3" barrel.
Shooters and law enforcement typically choose the 11.5" barrel, as it has better overall performance, especially in the heavy (SOCOM) profile. Our LE customers tell us that they will only use Colt barrels in 10.3" to 14.5" lengths. Colt truly does dominate that market, while other barrel companies own the long-range and sniper market.
All NFA laws apply. If you are uncertain if you can own this, check federal National Firearms Act, also with your state authorities. I am not your lawyer. You need to make sure you can own it.
Note: All ITAR regulations apply. Charlie's deals in the real McCoy. Your item most likely has parts that cannot be shipped outside of the USA, or owned in the USA by non-US Persons. You take accountability to safeguard parts and the entire upper, and get necessary approvals to transport outside of the USA.
Please feel free to ask questions before you buy.