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

Awesome thanks guys, I was hoping the answer was the unity riser.

Closer to being complete. Lower UID now on (not pictured). Just need some Magpul offsets now.  

Replicating ish this NSW setup.

Needs laser.

Needs mostly optic/mount and laser.  Not sure what optic yet.  Leaning towards LPVO.

Wanted to try it too.

Yall and yalls  not clone correct and non fixed mount wmx200s are disgusting!!

That turned out great!!   I do love the elevated Eotech over the standard lower 1/3 height.

I thought about putting the fixed one on there to make it more exact.

You need to cause it's killing my clone ocd lolol

Agree.....what the hell is keylows thinking.....?

Mods please ban. ^^^

I see the black unity risers in the last few posts, and the one coyote at the bottom of the last page….
Anyone have the coyote/tan unity riser under a tan exps3?

Can’t decide on which color.

OCD restored and added some MP offsets.

Damnt wakebrdr, thanks for the pics, but I can’t figure out which one.

The black unity and tan exps look awesome together.

If I were to do it again I'd go black. Wasn't really cloning a specific unit at the time but here is an Old pic:

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Su233 riser:
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Some times I miss this rifle.

Both sick!!  I’d miss them too.

Both look boss! I really like that insight riser.  Hoping I eventually find one of those.

So close yet so far away

Nice! A fellow GG&Ger….

Glad I found this thread! I want to find the mount for the clone of my issued rifle, and then manufacturer’s website doesn’t have it listed. Anyone seen one of these mounts out in the wild, and know where I could find one for sale?

Looks like their lower 1/3rd micro mount. Not sure about the plate below the optic.

It’s close, but this one is absolute co-witness, and has all those extra pieces making up the riser portion. Plus, the button on mine sticks out a bit more and has a small locking tab pressed into the flat actuator bar that keeps the button from getting pushed In accidentally.

I can’t find anything like it on the internet, and I wonder if it’s a contract piece for government use, from some contract somewhere. I don’t know where our weapons came from, but they’re not trash like I’ve seen on some other contracts.

Double tap

Maybe try asking if your unit armorer can find out if it had a contract or if it was a personal purchase from the last guy using the rifle?

That’s the direction I’ve been leaning toward, and I’ll be headed back to the compound where I drew my weapon in the near future, so I’ll get a chance to ask one of the armorers about these mounts.

I’m hoping I can find a source for them, as I’d love to have a clone-correct copy of my current issued rifle. It’s one sweet piece and it shoots better than I can hold.

My last qual was a couple weeks ago, and was actually a lot of fun due to the gratifying accuracy and ease of handling of this little rifle.

I had never really given the Mk.18 much thought before, but using them in training and then getting issued one here, I got to know it pretty well, and I have to say, I LOVE IT.

Shoot KDG an email too. Maybe they'll have one you could purchase.

Anyone have an issued cqbr with fde afg2 pic handy?

Thanks, looks good but that's an afg1. Ended up grabbing a full size TG QD VFG. In all my different builds I never used one of those.

In the trash can outside the armory…they all got replaced with factory mounts because those were loose and bent when dropped.

SF muzzle brake
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Get started on your CQBR Block II build…

URG for sale

Yes I’m looking at the rifle too….but anyone know what the footwear is that he’s wearing?

Currently putting together a mk18ish build.

any input on crane spec colt socom cut down barrels(w/fsp pin cuts) vs. having a 14.5 socom cut to 10.3 (less the fsp pin cuts). vs  a gov profile DD barrel?

I had ADCO cut my Colt Socom barrel to 10.3 and shave the FSP. Not sure if that is clone correct but I am very happy!

For a Block II URG/Mk18 Mod 1 with DD Mk18 RIS
Crane cut down factory Colt 14.5" Govt profile to 10.3" and dimpled the barrels.  I have never seen a Crane cut down 14.5" SOCOM profile to 10.3".  Factory 10.3" SOCOM bbls in system are from FN or KAK (7YV73).  I have seen NSW using DD Mk18 uppers so assuming they had DD barrels.  Never got to take one apart.

Mk18 Mod 0 with Crane cut down a Colt Govt profile bbl
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Mk18 Mod 1 with FN SOCOM bbl
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Left Crane Colt cut down
Middle FN SOCOM
Right KAK SOCOM

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Can we get an issued rig with T1/T2 photo dump????

You never said as the primary optic
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@Combat_Diver

Thank you sir.

I questioned cut down 14.5 socoms as I have seen a few guys doing so.  Maybe due to availability

Seen SEALs run the same in UAE (minus paint and different light) as mine
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Others have gone your same route.

I'm too poor to run it as a secondary! Need primary. About to rob the T1 off the recce as I literally have shot with it twice. If I ever get some nods I'll throw it back up there.

Ahh nice. Didn't realize there were cubby pics lol. Always thought this was a cool non-vanilla gun.

Missed one lol Attached File

I never noticed. I was always distracted by the lupy on the Fn launcher lol.
Alright alright, I'll calm it down on the mutt clones.

Per the request here's 5 with 5 different mounting solutions.

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These lil rifles are heavy enough for their size... I went with gov't profile. IMO the extra weight negates anything the heavier socom barrel offers.

KAK .... Didn't know they had a dog in the fight.