AR Sponsor
Posted: 11/21/2011 2:50:35 PM EDT
| Can somebody please tell me, on an M4 type barrel, what the contour is called, that is just behinf the FH? I am talking about the odd "cutout" that is in the barrel, that differentiates it from an Gov. profile barrel. Thanks, 9080 |
|
Quoted:
Can somebody please tell me, on an M4 type barrel, what the contour is called, that is just behinf the FH? I am talking about the odd "cutout" that is in the barrel, that differentiates it from an Gov. profile barrel. Thanks, 9080 It's so you can mount an M203 grenade launcher. The ones with that cutout are government profile. |
| Hey EP, the "Gov. Profile" I was in reference to was more like the A2 style. In another section of the site, I used the term "M203 cutout" describing an M4 type barrel, and there was a bit of confusion. I just wanted to make sure that I was using the right terminology. Thanks, 9080 |
|
"M203 cut" or "notch" seems to be the most common and preferred terminology.
Your confusion may have come from me when you asked about M4A1 profile barrels, USGI RO921HB M4A1 Carbines have a different profile barrel than standard RO920 or RO977 carbines. The latter have the "government" profile under the handguards, or "wasp-waisted" barrels, while the RO921HB barrel used on the M4A1 has a medium contour barrel that gets progressively thicker as it approaches the barrel nut. Because of this thicker barrel, standard M203 mounts cannot be fitted on this thicker profile unless recesses are cut into the barrel about a third of the way between the handguard cap and barrel nut. These are also often called "M203 cuts" or "M203 flats." This profile is commonly (but incorrectly) known as the "SOCOM profile" barrel (SOCOM being the principal user and purchaser of the RO921HB M4A1 Carbine). Both Stag and PSA, among others, have released heavier profile barrels under the handguards that do not have M203 flats under the handguards, but M203 notches forward of the FSB. This is among the silliest of barrel profiles, because the M203 notch serves zero purpose, because even if the user had an M203, it could not be mounted to that barrel. Colt's RO921HB barrels, BCM vaporware "SOCOM" barrels, and CMMG's discontinued "M4A1 SOCOM" barrels all had the M203 flats as well as the M203 notch. For the time being, Colt is still the only provider of properly "spec'ed" M4A1 HB barrels (BCM hasn't had a production run of these barrels in over a year). PSA is selling a 16" barrel that they refer to as an "M4A1" profile, however it lacks M203 flats under the handguards. Colt also produced a small (~300 ea.) run of LE6920s with 16" versions of the RO921HB barrel for SAW that they referred to as the LE6920HB. Note, however, though Colt refers to these barrels as "HB" (Heavy Barrel) they are not "true" HBAR profile compared to "accepted" industry standard, or in comparison to Colt's other HBAR offerings [like the AR6721], but rather are closer to a medium contour. ~Augee |
AR Sponsor