When discussing the Mk 18 / CQBR program, we can divide the history and discussion in to two distinct categories: 1) The weapon system itself / upper receiver supplied and 2) the group of accessories deployed on said weapon systems (SOPMOD).

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Mk 18 Mod 0 / CQBR

The M4 carbine and M16 are not ideally suited for all missions, so it was proposed that the modularity of the M16 series would allow a user to replace the upper receiver of an existing weapon with one more suitable to the task. One of two proposed special mission receivers that were planned for inclusion into the SOPMOD Block II kit, the CQBR has taken off on its own. Like the proposed Special Purpose Receiver, the Close Quarters Battle Receiver has been more or less taken on by the Naval Surface Warfare Center, Crane Division (often referred to as NSWC-Crane or just "Crane") as its own project following the CQBR's removal from the SOPMOD program. Just as the Special Purpose Receiver morphed into the Special Purpose Rifle, and was type-classified as Mk 12 Mod 0/1, the complete CQBR-equipped carbine has been type-classified as the Mk 18 Mod 0.

The purpose of the CQBR remains to provide operators with a weapon of submachine gun size, but firing a rifle cartridge, for scenarios such as VIP protection, urban warfare, and other close quarters battle (CQB) situations. The CQBR is designed to provide improvement over previous AR-15/M16-type weapons in this category. The CQBR is usually issued as a complete weapon system, and not just an upper receiver. The CQBR was once only available to Naval Special Warfare units, but the Mk 18 Mod 0 has become general issue for Visit, Board, Search, and Seizure (VBSS) missions and, as of 2006, for NCIS agents deploying to active combat zones.[citation needed] The Mk 18 is also used by the Coast Guard's Tactical Law Enforcement Teams, Maritime Safety and Security Teams, and Maritime Security Response Team and the United States Navy's Explosive Ordnance Disposal (EOD) Operators.

Wikipedia has a good article with sources on the original CQBR/Mk 18 Mod 0 and its development.

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SOPMOD

The SOPMOD Program Management Office at NSWC Crane, IN, provides standardized, versatile weapons accessories to meet needs across SOF mission scenarios. These accessories increase operator survivability and lethality by enhanced weapon performance, target acquisition, signature suppression, and fire control.

The CQBR itself was originally part of the SOPMOD program as an accessory replacement upper receiver for the M4. However it was eventually separated out into its own project.

SOPMOD accessories for the M4/CQBR originally included things like the KAC RIS/RAS, SOPMOD stock, KAC M4QD suppressor, AN/PEQ-2 illuminator/laser, ECOS-N red dot, ACOG, etc

The SOPMOD program has gone through multiple minor and major evolutions throughout its lifetime. The most significant is commonly defined as "Block II" and included the introduction/replacement of accessories that met the updated needs of operators. The most visually significant "Block II" accessory is probably the replacement of the KAC rail/FSB with the  Daniel Defense RIS II free float rail with low-profile gas block. Other updates include things like the Surefire SOCOM sound suppressor, EOTech RDS (553/SU-231 & EXPS 3-0/SU-231a), LA-5/PEQ ATPIAL, etc

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Link to docs and photo albums

 Presentation on CQBR from Crane
 Operator's Manual for Mk 18 Mod 0
 SOPMOD Program Overview presentation from Crane
 Photo Album of Mk 18 Mod 0
 Photo Album of CQBR with SOPMOD Block II accessories

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Because of the long history of both the CQBR/Mk 18 and SOPMOD programs, it's common to find weapons with various mixed configurations in the field, all depending on what time and unit the weapon system belongs to. Below are a few examples with descriptions to illustrate this.


Example of a Mk 18 Mod 0 in as-issued configuration including: M16A1 surplus lower receiver, SOPMOD buttstock, KAC RIS, KAC M4QD flash hider, Aimpoint Comp M2 in Wilcox mount, LMT rear fixed sight, CQD rear sling plate.


NSW Operator CQBRs with original SOPMOD accessories including KAC M4QD sound suppressor and AN/PEQ-2 IR Illuminator/Laser.


Member of a Combat Camera team with a CQBR with KAC RAS and M4QD flash hider but with other updated accessories from the "Block II" SOPMOD kit including SU-231a (EOTech EXPS 3-0), EOTech G33 Magnifier, LA-5/PEQ ATPIAL, Insight WMX-200.


Good example of "early" CQBR with SOPMOD Block II accessories including SU-231 (EOTech 553) and SU-233 (Insight M3x weaponlight).


Example of a more "modern" CQBR with SOPMOD Block II accessories including the updated SU-231a (EOTech EXPS 3-0) and Insight WMX-200 weaponlight.


Many times certain configurations are common within certain branches/groups. Here a Marine Raider is seen with a CQBR with an AN/PEQ-16 (USMC issued vs. the LA-5/PEQ SOCOM issued ATPIAL) and KAC NT4 suppressor (vs. the current Surefire SOCOM suppressor).

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Building a clone

If you're interested in building a "clone" of a Mk 18 or CQBR equipped M4A1, here is a basic parts list to use as a guide and get you started. This list is not exhaustive and see the * note above regarding personalized accessories.

                       | Mk 18 Mod 0                      | M4A1 CQBR Block I                   | M4A1 CQBR Block II                                      
Lower Receiver         | Mil-spec forged A1               | Mil-spec forged A2                  | Mil-spec forged A2                                      
Stock                  | Gen 1 SOPMOD (Black)             | M4, CAR, SOPMOD, CTR & others       | M4, CAR, SOPMOD, CTR & others                            
Pistol Grip            | A1                               | A2, ERGO & others                   | A2, ERGO & others                                        
Rear Sling Plate       | CQD                              | CQD                                 | CQD                                                      
Upper Receiver         | Mil-spec forged M4 profile       | Mil-spec forged M4 profile          | Mil-spec forged M4 profile                              
Barrel                 | 10.3"                            | 10.3"                               | 10.3"                                                    
Rail                   | KAC RIS                          | KAC RAS                             | DD Mk18 RIS II (FDE)                                    
Rear BUIS              | LMT Fixed                        | LMT Fixed, MATECH, & others         | MATECH, KAC 300m, & others                              
Front Sight            | A2 FSB                           | A2 FSB                              | KAC 99051 BUIS (Taupe)                                  
Front Sling Attachment | FSB Sling Swivel                 | FSB Sling Swivel                    | CQD                                                      
Muzzle Device          | KAC M4QD                         | KAC M4QD                            | SureFire FH-556-RC                                      
Supressor              | None                             | KAC QDSS NT4                        | SureFire SOCOM556-RC (FDE)                              
LAM                    | None                             | PEQ-2                               | LA-5                                                    
Weaponlight            | SureFire M962                    | SureFire M952, M962                 | Insight M3X (Tan), Insight WMX200 (Bronze)              
Optic                  | Aimpoint Comp M2 in Wilcox Mount | Aimpoint Comp M2 in QRP Mount, ACOG | EOTech 553 (Tan), EOTech EXPS3-0 (Tan), ELCAN 1-4x (FDE)

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Link to previous threads

 Previous Mk 18 / CQBR Thread Part I
 Previous Mk 18 / CQBR Thread Part II

It makes me happy seeing all the DD barrels, I cannot lie!

Lol I'm sure. It sure makes the log train/cost a lot easier for many of us.

I paid to have my Block I and II Colt barrels cut down, and it's quite the sticker shock.

I missed out on the full kits but snagged a rail and C marked keyhole upper kit.

Nice! I missed out on both unfortunately.

Yes, FN socom barrel, 4/15 date with B stamp on the side.




Guess it's my lucky day, rail is Black Creek from Oct '14, bottom rail is a Savannah from Aug '06.

Nice. Even scored a ris ii with date and lot no. Those are fairly hard to come by. Up there with savannah marked.

Right. Pics or it didn't happen!

Man, I really missed the boat on those. Very nice combo. Not sure on the price they charged, but can't be any worse than what mine was pieced together.

That X... marking is a NSW Mk18 inventory number. Just before they switched to the 10.... and 14.... inventory numbers.

Daniel Defense barrels have been a thing for a few years-
USSOCOM BOLT & BARREL KIT INCREASING USSOCOM OPERATOR READINESS WITH CUSTOM KITTED SOLUTIONS
THE CHALLENGE:

Naval Surface Warfare Center (NSWC) CRANE Division was fielding M4 Upper Receiver Groups (URGs) outfitted with 10.3” Barrels to U.S. Special Operations Command (USSOCOM) Special Forces Operators. Unfortunately, there was no source available for 10.3” barrels through the existing supply system. To support sustainment, NSWC Crane improvised by procuring 14.5” barrels and cutting them down to specification through a lengthy and expensive process that, in many cases, left operators without their M4 for months at a time.
When NSWC Crane had an immediate need for 1,407 10.3″ barrel replacements, there was an opportunity to provide a more efficient and cost-effective solution to address their requirement. Our weapons subject matter experts consulted with Daniel Defense, our partner manufacturer, to identify all of the items required to complete a 10.3” barrel change on an M4 URG. Our kitting experts and Daniel Defense developed a low-cost complete kitted solution for the barrel replacement procedure—the 10.3” Bolt and Barrel Kit (10.3” BBK).
Our logistics experts assembled all the components into 1,407 individual Bolt and Barrel Kits at our warehousing facility.

Each kit was packaged securely inside a reinforced cardboard tube to ensure the components were protected during transport and storage. Additionally, the kits were delivered with a full bill of materials for simplified receiving and inventory control.

Supply Chain Management
Warehousing
Kitting & Assembly
Custom Packaging
Distribution & Transportation
We reduced sustainment costs for NSWC CRANE by roughly $95,000 through the creation and procurement of 1,407 BBKs through our GSA Schedule vs. obtaining the same components individually through the NSN system.

Additionally, we provided intangible cost savings by decreasing the down time of their Operators waiting for maintenance to be completed. We also increased the efficiency of NSWC CRANE’s logistics and maintenance personnel involved in the repairs by streamlining and simplifying the process through a kitted solution.

I picked up 1 of those surplus DD MK18 rebuild kits.
Included parts
Barrel
Bolt
MK12 gb
Gas tube
Firing pin
Retaining pin
Attached File

Using the dark side of the clone force, I naturally foresaw their eventual correctness before going with DD barrels ;p.



Yep, pretty old news; I think I've posted that link a half dozen times, lol.

Still, it's nice to have it reconfirmed from a separate source, and there to be no doubt good evidence of them being fielded.



Nice... wouldn't mind having one of those. Although, it's basically just like one of the rebuild kits I've put together for my Block IIs -- the only real difference is that mine have complete Colt/TC BCGs and the Mk12 is in retail packaging.

But having a legit surplus kit would be nifty.

My comment was meant as a joke more than anything. Just rehashing the good ole days in my head. Lol. I mean, is that pic really even from the field? I mean I could prob find a pic of a rusty andro corp barrel and post it, doesn’t make it issued. Just messin. Honestly.

It's from the Thoroughbred kit I just got. No idea on provenance other than that.

That is a really cool kit though. And it's really cool to see some more dd barrels. Can't wait to see it built up!

ETA- are the dd barrels chf?

Believe it says so on their website

Yup.

The "F" stands for forged.

I knew their civi barrels were chf, just wasn't 100% sure if the gov were getting the same exact barrels or not.

[poop]

Paying $300 for a new condition C Keyhole colt upper. Please send a message!

Oh my...

Looks like you got one of the .mil DD barrels. First evidence I've seen of them being used on a Block II URG. Seems legit since it's paired with a 2013 RIS II. These were dimpled for the Mk12 gas block and had a .070" when their commercial barrels were way overgassed. I believe the surplus ones were sold through Western Sport. I think it was around 2015 when these were made.

Cool!  Thanks for the info.  ETA. Which upper to go along with it?

Attached File


Gen 2 sopmod on the ground.

I want to be part of this frantic grabbing scene.

What optic is on the rifle in the bottom center?  The one with the magnifier.

My MK18 Mod0 on a SBR PWA lower.

I have a salty black non-padded vtac that would go well with that gun.

Attached File

leupold LCO

Is that a..... 10.5?

I saw that and got sidetracked by the sling.  lol

Does anyone have a source for a .070 DD 10.3" barrel?

Think there's one in the used upper receiver section of EE

glitch

Should be able to source it direct from Daniel Defense.  If out of stock sign up for an alert.  I’ve noticed their barrels come back in stock pretty often.

I don't know why I didn't think of that.

That's hot. I have a new upper coming from specialized armament and I still need the KAC rail and a Colt lower.

DAT SCAR DOE!

Request for info; MK18's & Sopmod stocks.

Hey guys, thought this would be the place to ask. I have a B5 Sopmod I got years ago on a safe queen (non MK18) that was sold to me as govt contract overrun in a mylar bag. It's B5 brand but no logos on it, just cage code and no QD cups. I understand these were associated with MK18s. Any specific value to these for cloners? If so then I'd be inclined to pass it on to someone with that in mind. I like the stock just fine but want a stock with QD onboard. Any info appreciated.

Looks like every stock ever made is in that photo.

Their value isn't anywhere near the LMT stocks. Brownells is selling the .Gov stocks for $95.00 currently.

Shouldn't be anymore than what Brownells is charging for them. B5 GUBMENT ISSUE SOPMOD
You can still find them scattered around IG stores and the usual suspects around here.

I wouldn't say they are specific to MK18s/Cqbrs, just another standard issue stock option for .mil issued small arms.

Figured this would be the place to ask - what’s the current going rate for an SU-231 marked tan 553 with a good window/reticle and some external surface wear?

Thanks guys. That's all it's been for me. Didn't think they were unicorn poop but saw that they seem common on clone guns. I'll probably find something that works for me then move it on in the EE at that time. Thanks again.

Regular old stock bukkake

Yummm.  

It's been a pleasure knowing you all, thanks for all information over the years.

Just incase arfcom gets deleted from the internet.

Read that Go Daddy dropped us, but they’re working on finding an alternate host. Go Daddy is headquartered here in AZ.

If you guys haven't already, add AR15.com's direct IPs to your hosts file or save the IPs to go there directly.

3.138.255.236 ar15.com
3.139.193.203 ar15.com
3.20.37.167 ar15.com

While they'll possibly get around to pulling the AWS hosting, it's still up and accessible directly for now.

There is also: https://www.ar15-backup.com/