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Posted: 12/4/2004 1:16:10 AM EDT
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Was hoping those with more experience could lend of their knowledge. What exact parts and labor would be required to change a Colt Blue Label Model 6731 16" H-Bar Post Ban upper to a Colt M4 USMC No Ban Upper. Request Opinions on Specific parts required. Request Opinions on Specific Vendor for parts required (Ex: Colt, SAW, Wes, ect) and Request Opinions on Specific Vendor for assembly required (Ex: SAW, Wes, Steve, Kurt, ect) Opinions, suggestions, advice. Thanks. Semper Fi |
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Hey Lumpy. I was referring to this upper: M4 CARBINE MODULAR WEAPONS SYSTEM SOL M67854-00-R-1030 DUE 042800 POC Dwight B. Micheal, Sr., Contracting Officer, Code CTQ1DBM, (703) 784-3367 E-MAIL: Click here to contact the Contracting Officer via, [email protected]. The Marine Corps Systems Command (MARCORSYSCOM) has a requirement for production and integration of a M4 Carbine Modular Weapon System. The M4 Carbine Modular Weapon System's characteristics consist of the integration of the M4 5.56MM Carbine, NSN 1005-01-231-0973 and the M4 Rail Adapter System, NSN 1005-01-452-35273. The M4 Carbine is a lightweight, gas operated, air cooled, magazine fed, selective rate, shoulder-fired weapon with a collapsible stock manufactured according to the guidance specified under Military Specifications MIL-C-70599A (AR). The required delivery quantity for this production and integration effort is 2,623 units with a required period of performance of approximately three months after contract award. MARCORSYSCOM intends to award a sole source contract to Colt's Manufacturing Company, Incorporated, P.O. Box 1868, Hartford, Connecticut, 06144-1868. Colt's Manufacturing is the sole designer, developer, and manufacturer of the M4 Carbine and as such, is the only contractor qualifiedand capable to fulfill the Government's requirement to manufacture the M4 Carbine and to integrate the carbine with the M4 Rail Adapter System within the required delivery period. See Numbered Note 22. Posted 03/17/00 (W-SN435741). (0077) Was considering installing a Colt 6921 barrel (is 14.5", has M4 profile, A2 threaded, 16"oal). Was asking if I needed Mods to BCG, gas syrtem, buffer, ect for system to operate correctly afterwards. Srry. Didn't mean to sound ignant. |
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All you'd really need is the M4 barrel assembly and handguards. You could reuse the existing gas tube and roll pin, although as inexpensive as the roll pin is you might as well replace it, too. As far as the cost of having it rebarreled, I'd think you could find someone to do it for $50 or so. I bought an action block and armorer's wrench and did the work myself. It's actually petty simple. You also can't legally use the LE6921 14.5" barrel without registering the weapon as a short barreled rifle or permanently installing a muzzle device that brings the overall barrel length out to over 16". |
That is the problem, the 6921 barrel is NOT 16" OAL, maybe you are wanting the 6920 which is the same, but is 16" long. Although it won't be "correct" since the Military barrels are 14.5" (6921 barrels)..... |
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Thanks to all for help and info. I am considering buying a new Colt Barrel, either the 6921 or the 6921hb. I would use a new roll pin. It would be worth it to me to have this upper re-barrel by a smith. This is my favorite rifle, not a beater I want to learn on. I already have a KAC M4 RAS, which is presently mounted on my existing 6731 Match Target H-Bar upper. I would like to use the M4 RAS on the re-barreled upper. I am thinking that the 6921 barrel has the true M4 contour under the handguards and that the KAC M4 RAS will fit this barrel. Can anyone advise? I am thinking that the 6921hb is a heavy barrel version of the 6921 barrel, having a barrel thickness under the handguards similar to an H-Bar. Seeing how my M4 RAS fits my current 6731 H-Bar Barrel, I was thinking the M4 RAS would probably fit on the 6921hb as well. Can anyone advise? Any opinion as to an advantages/dis-advantages of the 6921 and the 6921hb barrels? The 6920 vs the 6920hb barrels? My plan was to get the 14.5" barrel (6921 or 6921hb) and add an A2 FH to make the OAL 16". Confirm I would have to perm install A2 FH to make this legal or could I go threaded route? Would a 14.5" barrel with perm attached A2 FH for 16" OAL be legal, and a 14.5" barrel with threaded A2 FH for OAL be illegal? If neither is legal then I guess I will have to consider the 6920 and 6920hb barrels with same questions about A2 FH? I also was unsure if going to a shorter (14.5", 16" OAL)/different barrel, would require changing anything else, (barrel extension, BCG, gas system, buffer assbly, ect) for rifle to function properly, (cycling rate, ect). |
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Would a 14.5" barrel with perm attached A2 FH for 16" OAL be legal, and a 14.5" barrel with threaded A2 FH for OAL be illegal? No. The A2 flash suppressor is too short (~ ½" -ish) to make the legal 16" minimum. You would need to permanently install a Phantom or Vortex flash suppressor to make the 16" length. |
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I know from past experience that Wes, Kurt and Steve provide outstanding service and do excellent work. The extended A2, phantom and vortex are all good options. Have never had a perm attached FH though. Would like to more opinions from folks who have gone this route. Also looking to get opinions on comparisions in 14.5" and 16" barrels, with regards to performance, handling, likes and dis-likes. |
i have Colt M4 upper 14.5" with perm attached Phantom, unless you have the need to remove your FH, which i don't, it's not a problem. but in the event you want to change FH in the future it can be done. as far as comparing the barrels is concerned, handling won't be noticable(.75" difference. 16" + A2 vs. 14.5" + phantom) performance would be an issue if your shooting things other than paper. longer barrel = greater velocity at longer range = yaw & fragmentation = tango down. but you won't notice a difference in accuracy. personally i like the 14.5 better because it looks cooler, i hate the way a 16" barrel looks( unless it has full or midlength rail ) i wish i had known about the extended A2 when i did mine, would have went that route. |
| RAS should be fine on the 6920HB and 6921HB barrels. They fit on Bushmaster HBars as well. They won't work on Oly or RRA Hbars, though. Personally, I'd get the 16" for better performance. It won't be an exact clone, but performance always trumps appearance in my book. |
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