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

Kinda cool that an m4 is hanging around at an airport waiting for a flight

And that thing is a mixmaster. Just how they all are.

NGAL and thennnnn the shittiest white light.

Of all the lights you could pick that’s the one?

Okay.

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Finally found one

I’ll take it! Jk congratulations let me know if you find anymore lmao

What is market?  I have quite a few lol

I'm curious to know what the current going rate is for one too. Lol

Around 750 for fixed NAVSEA ones double for rotational NAVSEA

Hell I just want an FDE fixed one!

Anyone know the going rate for a Wilcox M68 mount?

In a moment of weakness, I just sold one attached to an M2 for 350.00

Damn!

I haven't looked for a few months, but last one I saw was listed for $180 on the EE

@bradpierson26

What block are you going for?

Got the 249F installed today! Anyone have one of the older non logo versions? Could only get a quarter turn out of it. Pinched the washer pretty decent but think it’s shouldering out.

@tanodized

It was years ago I swear I saw an lmt marked 10.5” in use. Maybe my eyes and memory deceive me.

Disregard

@fadedsun
Just an original mod0

80% clone lower arrived

Some build progress:

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Where does one procure an 80% Clone lower like that??? 👀

I tagged you in the GD thread and I’ll send you a PM

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Upper and BUIS arrived. Sf4p coming. Kac rail coming.

Need to change the pg on my lower to an a2
And add a geissele ssa-e. Nobody will know until they shoot it  

Superb. 80% receiver thread link and what rear sling mount is that?

https://www.cqd.net/store/CQD®-Rear-Sling-Mount-p201128433

The make a front mount as well.  Are you putting together a Mod 0?

There’s a subtle difference between commercial and mil A2 grips if you care about the minutiae.

You don’t want this line:



Vs. Colt:

Fuck my life
So this is commercial?
Source for Colt?


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80% lowers

ORjeepguy provides the 80% blank and engraves how you wish. Super quick turnaround
@fadedsun

Ummm kind of


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https://coltparts.com/colt-ar15-m4-pistol-grip/

https://wetworxoutfitters.com/surplus-colt-a2-grips/


https://wetworxoutfitters.com/colt-m16a2-fatty-grip/

To my eye, that looks like a Colt “F3” grip.  Peek inside by the screw and see what the marking is.

Colt has gone through a bunch of A2 grip variations.  Old and shiny, fat and chalky, then a cheap version that was the same as Damage Ind. was using.

@fadedsun

Basically, avoid that pronounced straight slanted line in the first pic I posted.

I know we’re mortal enemies in Uke threads, but not actually though.  I’ve got a shitload of Colt A2 grips laying around.  If you’re in need I’ll send you one gratis.

I was actually going to tag you as a reference on Colt grip variants.

Like you said,  it's a shit show when it comes to Colt's grips.


ETA:
1983-1998 / Slightly wider and a different contour than current production. #SP6457

Current Colt/ #SL00005

Thanks, Tig! That’s the kind of knowledge I was looking for.

Thanks
So a 6457 should be correct for an original mk18 mod0 that woulda been sourced from existing guns?

I would say that a Colt A2 grip , regardless of flavor, would be correct personally. (As with one of the various subcontractor grips.)

Both Colt grips were available on issued guns and I'm fairly certain that both are still in the supply chain.

@Combat_Diver would know for sure. I'm just a civvy spectator..

Another that you just take for granted and don't pay attention to.  Only those that stand out have been worn done smooth and shiny!
Old Colt has campaigned hard
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I still find that grip cool. I remember when you first posted pics.

This one was in Syria.  Other well worn smooth was on serial number W000489.  Under first 500 in 94' as I posted in Astan several years ago.

Since these guns belonged to the 82nd ABN DIV, wonder how many jumps they made?
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My mistake, I assumed they were one and the same.

Wow, those should be in a museum!
Awesome man!

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The real flex in that pic is the glock. lol

17 or 22?

What do we think the light is on this middle rifle?

Mine only went with me about 6 times in 2 years, but I was a staff puke. I rode my weapons case in one time when the tie down tape didn't pull out on my way down. It wasn't a problem and I had planned if I ever had to jump in a real world event that I would drop my ruck, but keep my rifle next to me. I also jumped with TAPS and all of my mags ready to go for combat equipment jumps with a follow on mission. It kept weight out of the weapons case which sucked on racetracks or in general because it would be at the top of the case.

What are the chances of finding/getting an NT4 these days?

$3-5k depending on condition on gunbroker.

The last time I heard about anyone getting one from a retailer was @eyekhan and I think it was a few years ago.

Zeroed Ole reliable last weekend

17
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No worries, this ain't about Ukraine or anything else, this is about CQBRs and Mk18s

I already have a PG on the way, so don't worry but thank you for the offer! I ordered it about an hour before I posted the pic you responded to.  

It will go on my 99% clone correct CQBR block 1.5

I used to have a ton of them around and I got rid of a bunch before I started cloning and used the rest on my a2 projects. Now I actually had to go on GB to get one. Shame on me



I looked and found one. WTF

4k for a can that's technologically behind something 1/4 of the price?



That grip has more TIS than I do. Bloody hell.



That's super cool. It's a shame I already have a surplus NFA lower to use otherwise I'd do that.

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This build is the reason why I joined ARFCOM in 2019.  Special thanks to Combat_Diver for technical questions answered in the thread.

Cheers!

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Waiting to install the:

SF4P
A2 PG
H2 buffer + new spring (it's a used lower, bought new in 2016)
SSA-E..supposed to arrive tomorrow.

Are front side sling swivel mounts correct?

Is the SOPMOD on it a gen 1 or 2?

The one in your pic? That is a Gen 2 (QD attachment instantly lets ya know)