Colt FBI HRT 11.5" SOCOM barrel M4 6933 w/FSB

Colt FBI HRT Heavy 11.5" barrel with Front Sight Post "SOCOM" Style

When the FBI wanted a short Colt, they didn't settle for the standard Commando profile. They asked for more steel. This is that barrel, 100% Colt, exactly as Colt made it: chrome-lined, 1:7 twist, a Colt factory-pinned F-height front sight base, and a suppressor-friendly 0.070" gas port. Marked with Colt's CAGE (government contractor) code and ready for your 6933-style short-barreled rifle (SBR) or pistol build.

More steel than the Commando

Colt's standard 11.5" barrel is a lighter government profile, slim under the handguard. This one is the thick SOCOM profile, the same contour as Colt's 14.5" SOCOM barrels, minus the M203 grenade-launcher cuts. Builders also call it the FBI profile, because it is the barrel the FBI's Hostage Rescue Team chose for its rifles. That extra steel under the handguard soaks up heat on long strings and resists heat-driven point-of-impact shift better than a lighter profile.

This is a Colt factory barrel, not a cut-down and not a shop reassembly. Colt chambered it, lined it, tested it, and pinned the front sight base. Nobody has touched it since.

Short, smooth, and suppressor-friendly

Eleven and a half inches is the Colt Commando length, and on a carbine gas system it is the sweet spot for a short barrel. It cycles more smoothly than a 10.3" or 10.5" and gives up very little in handling, and the 1:7 twist stabilizes heavy 77-grain match loads. The gas port measures 0.070" with pin gauges, sometimes a touch under. That conservative port makes this barrel more manageable suppressed than many commercial short barrels, with the right buffer and spring.

F height, by the spec, not the stamp

The front sight base is the gas block, and Colt pinned it at the factory, bayonet lug and all. It is F height, the correct height for flat-top uppers and for every short barrel. Effectively every carbine-gas barrel Colt makes is F height, so Colt has largely stopped stamping the "F." We go by the specification, not the mark.

A note for HRT purists: the Bureau ran this profile without a front sight base. If you want that configuration, look at our Colt 11.5" SOCOM stripped barrel. If you want the classic Colt look, with the sight on the barrel and irons that never need batteries, this is your barrel.

Where it lives in your build

Installed on a stocked receiver, this barrel requires an approved National Firearms Act (NFA) SBR registration; otherwise, build it as a pistol where legal, and check your state and local laws. The 0.750" journal and FSB are standard, so it fits under Colt M4 polymer handguards and an M4 quad rail such as the Knight's Armament (KAC) RAS. The muzzle is threaded 1/2x28 for the flash hider or suppressor mount of your choice. Neither the gas tube nor its roll pin ships with the barrel, so plan on a carbine-length tube and pin. Each barrel ships heavily oiled in mil-spec packaging, either white plastic or blue VCI (corrosion-inhibiting) bags.

Slide it under a set of M4 handguards on a 6933-pattern upper, and you have a Commando with the heavy barrel Colt's standard model never got. Colt doesn't run these often, and they don't sit on our shelf long. If your build calls for the FBI profile, Charlie's would be proud to send you one.

Specifications