Mk18 Mod 0 enhanced CQBR upper receiver group with Colt 10.3" barrel

Assembled to Order, Ships in 2 to 6 weeks

Mk18 Mod 0 SOCOM enhanced upper receiver group - 10.3" CQBR

This is a Mk18 Mod 0 CQBR with enhancements

We started with a mil-spec Mk18 upper receiver group, and removed the clip-in M4 RAS and replaced it with a Knights Armament free floating RAS, which was an original upgrade to the Mk18.  The free floating RAS allows for the same attachment of multiple accessories, like flashlights, PEQ and a vertical grip, but keeps the pressure of the grip and the accessories off of the barrel, for better accuracy.

A rifle starts with the barrel, and we are using a factory Colt barrel, which has been prepared in the same manner in which NSWC Crane did back in 2001, which is to take a Colt 14.5" barrel, and cut it down to 10.3" and open the gas port up to 0.070" for optimal performance.  The barrel is a M4 profile Colt barrel with 1:7 twist and 5.56 NATO chambering and MP and high pressure testing, with chrome lining and a phosphated and oiled exterior.  The gas port change was actually made in 2017, but is now the accepted standard for a 10.3" CQBR barrel, along with using a heavier bullet, like the 77grain open tipped match bullet from Sierra, and found in the Mk262 rifle ammo from Black Hills.  We designed a military grade upper receiver with M4 feedramps and engraved T-marks from a mil-spec forging and hard coat 7075 anodized aluminum.  We added a mil-spec phosphated BCG with tool steel quality phosphated and chrome lined MPI and high pressure tested bolt made out of C-158 steel.

The CQBR upper receiver group is assembled by Potomac Armory, exclusively for Charlie's Custom Clones.


-- Mil-spec M4 upper receiver. Mil-spec perfection. 7075 military aircraft grade aluminum with hardcoat anodizing and M4 feedramps and engraved T-marks

-- Knights Armament M4 Free Floating RAS quad rail with 3 Knights Armament KAC ribbed rail guards. The real McCoy. The Free Floating quad rail was an upgrade to the first Mk18 design, and allows the operator to mount any number of accessories and not put pressure on the angle of the barrel, as a normal RAS rail would.

-- Mil-spec chrome-lined and phosphated bolt carrier croup, mil-spec phosphated finish. Note: for effective reliable shooting with a 10.3" barrel, you need a high quality bolt and carrier group, especially if you might be shooting rapid fire or suppressed. We have hand-picked our BCG from a Tier-1 supplier with tool steel phosphated carrier and staked gas key and Carpenter 158 steel bolt, MPI inspected.

-- PRI gas-buster charging handle. This is the crème del la crème of military charging handles. Yes, that is French. With suppressed fire or just rapid fire, an SBR is going to kick your ass with smoke and gasses. The PRI gas buster keeps the gas moving forward and out of your face.

-- Colt 10.3” Crane chrome-line mil-spec barrel with 0.07” gas port and carbine gas system with integrated FSB. We have taken a factory 14.5" barrel, and cut it down to 10.3", exactly as the first Mk18 barrels were done by the Navy armorers at Naval Surface Warfare Center Crane, in Indiana.  We have sent the barrels to one of the best barrel shops in the US, with a long history of providing military and precision shooting barrels, and had the barrels re-crowned, threaded and the gas ported opened to 0.070", which was a later improvement - much after the first Mk18's were cut in 2001. 

-- Colt A-Frame "F" height front sight base, factory installed by Colt.

-- Surefire SOCOM 3-prong flash hider. Bam! In your face, the Real McCoy again. The original Mk18's had either KAC or Surefire SOCOM flash hiders, and if you ever want to run suppressed, you want this flash hider and a Surefire SOCOM RC2 suppressor.

-- Magpul MBUS Gen2 rear back-up sight.  You may upgrade to a different rear BUIS, if desired.  Just ask the Charlie's team.  We found that people are either very picky about rear sights, like a KAC or Matech, or will want a great optic, like an Aimpoint or EOTech, and seldom notice their rear back-up sight.

Made in USA, not shipped outside the USA.


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Note: Any serial number(s) in photos are not necessarily the same serial number as the item that will ship. Also, for items where I am selling more than one of the same item, the pictures are meant to be representative of the item that will ship and show you the details of the item. Packaging also can vary, one item to the next.

All NFA laws apply. If you are uncertain if you can own this, check the 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 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 the USA.