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

I may swap it with another larue. Really want a lower 1/3 mount of some sort. I find it awkward to aim with fixed sights and absolute cowitness. Seems I can find Larue lt150 mounts cheaper than the wilcox mounts..

@Pneumagger

Barely any good paying contracts out there right now. That may change as tensions continue to build in the AG though...

Obviously designed to work in conjunction with the clandestine cow transport vehicle.

I hope this isn't going to start an "I seen it in the wild" trend with them.  They are only $40

Attached File

Mail man brought some replacement parts today

LMT gang


No hotdogs here

Is that a Colt full auto Ambi selector ?

I score a B5 contract stock. Just waiting on a few things and I will be part of the cool club

Indeed it is

I am waiting on PEQ 15 for bit too. But hey, at least, I don’t know, something

I just comfort myself with pictures and the occasional conjugal visit. It's like a long distance relationship :\.



Probably the final config with an N1 and the M300 set back so I can fully rotate the NT4 for removal.

That looks perfect.

Does anyone know where the KAC taupe front sight is in stock?

Thanks!
Jj

Unless that dude bought the last one, taupe was out of stock lol

Eta did we agree black was okay to use tho?

Thanks man but when you choose a color both taupe and black show 0 stock.

$190?

Keep an eye out in the EE. They pop up there for $160ish frequently.
I just got a new black KAC 99051 in the EE last week for $160.
The guy had Taupe too, but I wanted black.

I here ya man they seam to be $190 everywhere I look.....I've got a line on a black one for a bit cheaper I may just go that route.

My suggestion would be to wait until you can find a taupe. Bookmark all sites that sell them and sign up for their stock notifications. You'll find one within a week or 2.

I can't even purchase one...my local GS has alerts set up with every distributor for a tan NT4 and so far nothing.

Send a message to @doaarms here on the boards and Bobby will get you one.

Buy online. Form 3 to dealer

Thanks for the responses guys!.....so is black less common or not correct?

A couple cans of spray paint makes all your "clone color correct" woes go away.

www.clonerifles.com/theclones/cqbrblockii lists black KAC 55091 as good to go.
Plus if you think something's less desirable because it's black, that's raciss.

$165 Black: https://www.ar15.com/forums/equipment-exchange/Clon...1847339/

If the color of the “taupe” is at all important to you then you might want to see what you’re getting before you buy. Here’s a recent one I got 2 weeks ago next to some other stuff in various shades of coyote, FDE & taupe (KAC A2 grip).

Attached File


Attached File


In person they look WAY more gray than anything and not at all tan. Probably still fits the definition of “taupe” though. I hate them and they’ll be going in the EE shortly.

Hahah!!! now that's funny! Thanks for the help man!

Yeah I saw your original post on those......they do look a little funky I guess. I dont have the stones to rattle can.....yet.

Genofromreno still has black 99051 for 160ish in the Ee

If you DM or email him (whichever he prefers in his posting), he probably has taupe as well.

Yeah I sent him an e-mail.
Jj

Tan NT4 here

In stock NT4, black or taupe.

https://tarheelstatefirearms.com/store/index.php?route=product/product&path=24_59&product_id=329

Swapped out the Larue mount for a QRP, painted the vfg and mounted the peq.

What tan paint did you use. I like the shade

I love this movie!

Aervoe coyote, and then rustoleum (can’t remember the color, dark brown) over the top in the stripe pattern. If I went too dark with the rustoleum I would dust again with the aervoe.

nice amsec

Broke a atpial-c last week so picked up a new modern laser.

Nice man, looks like the mawl tucks pretty slick with the insight.

Thanks! I bought it on Amazon for a steal! BF7240 for $3272.

Curious how well the Illuminator works compared to the peq15 (full power).

@conner378

Recently got a RIS II for my build that is currently in a pistol configuration (SBA3).  Need input on my next big purchase: convert to SBR, or get a can?  I'm not super worried about being 100% correct with this build, but I'd definitely like to add to what I have by making/getting NFA items.  What do you guys think?

A lot of the parts I have aren't necessarily clone correct, but here's a list of what I have (mainly going for an aesthetic clone):
Lower:
Geissele Tricon Trigger
Geissele Buffer and Spring in a mil-spec tube
Magpul MOE grip
SBA3, will change it for a B5 once I make my decision on which NFA item I want first
Aero M4E1 stripped lower w/ parts kit

Upper:
DD RIS II w/ original hardware
10.5 Rosco barrel, gas block, gas tube, and bcg
KAC USMC marked rear sight
DD fixed front sight
EOTech Exps 3-0 w/ G33
SureFire 3 prong, want to get a can too
Aero stripped upper w/ parts kit