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

Thank you—I really appreciate it. Def felt some healthy pressure to represent our community well!

Blue screws out CONUS? Roger that.

Sick builds man.

Cant take credit for the 416, that's my buddy's. The other 2 are mine though

Does anyone have or know about the early gen 1 crane sopmod stocks? I have one (supposedly) and the color is tripping me out. Was the coyote color or whatever they called it kinda wonky on the prototype batch?

Attached File


I also posted one on the previous page. It looks almost od green. I'm starting to think it's a knockoff. It just doesn't feel like it is.

Is it possible someone dyed a tan stock? If not, does it have any CAGE codes?

For those of you using the RC/RC2 does it really cut down on gas to the face a noticeable amount compared to other cans you use?  Better than the NT4 for those of you that have both?  That comment about the gas on the Turbo got me wondering...and I wasn’t ever going to get an RC/RC2 but I’m getting the itch now.

No markings, blank squares where pat pending normally is, no cage, nothing. Checkered latch, reddish orings, no holes in tubes. Tight RE fit, was lightly reamed. I've read these things can be normal for early gen 1 prototypes, but the color is throwing me. But I've never seen a knockoff look like this. Was spray bombed before I stripped it. Guy I bought it from had high feedback and had been around longer than me and he said gen 1 early/tight.

Can you cut into the plastic in an inconspicuous spot and see if the color goes into the substrate or if it's superficial? If it's superficial, somone dyed it (or the paint/paint remover permanently stained it).

Looks pretty homogenous everywhere.

Its sexual preference has nothing to do with it's color.

I kinda like the green color, but I'd save it for another build and grab another Gen 1.

I considered just painting the stock faux taupe . I'd like to know what it actually is though.

Actually if I replace it on the cqbr, it's gonna be with a ctr. I don't really care for the sopmod anyway.

If you want to move it, I may know of a place it would be happy.

Looks like you're running low.

Very. Haven't bought one in a year or better.

Yes, the RC is pretty low backpressure, and it's less than an NT4. That said, with a properly ported .070" barrel and Gas Buster, it's not that big of a difference between the RC and NT4. Unless I make a conscious effort to note the difference, I can shoot the RC and NT4 interchangeably without really noticing a change.

I can't tell much difference between my rc1 and NT4 to be completely honest.

love both cans

Good to know now!  Now to find those RC’s that @wissota4 mentioned for under $600.

Yeah were those puppies at?  

I call fake news.

Lol. Not fake news. I had 65% off coupon for Surefire. I ordered direct from their website.

I keep hoping that’s not the case, but I can’t find anything under $900...I think I’ve been had.

Okay, logical follow up question is are your knees sore or did you where knee pads?


How in the crap did you find a 65% off coupon?!

Wasn't that the "Golden Ticket" that came with the URGI when they got released?

Actual Crane sopmod stocks are black and do not have any markings, the latch is same as the fiberlite Colts and they are smooth no texture at all.

The LMT first gen, well we know they are textured, and have markings, however prototypes may be unmarked and have color variances.

Yours looks very dark taupy, is the latch serrated?

Doesn't everyone have knee pads?

Those where like 30

I bought my current 556RC with either a 40% or 50% coupon.  I wouldn't pay full price for any can with regular deals.

I'll probably just get an RC2 since I've already ruined being clone worthy by going over to Geissele rails on my Block II's.

Ah

Good point

Latch is checkered.

Been looking to suppress my DD MK18 (10.3" and 0.070 gas block) but everywhere I go I see SF SOCOM RC2 sucks and loud. For those who thinks this is true, what cans should I look at? I have the RC2 in my cart ready to go but everybody's raving about the Turbo K on this forum. Somebody help me!

PS
This is for my home defense rifle/pistol or whatever they want to designate it as.

The RC2 is an excellent can. They sound great, but no 5.56 can is going to be "hearing safe" especially on a 10in SBR.

I don't expect ANY cans to prevent some hearing damage when shooting a 556 with a SBR. That being said, I'd like to be in the safe(?) zone with my COMTAC III on.

The RC2 sounds really good, and is a lot let gassy then most other 5.56 cans. They have less back pressure which helps with the sharp noise at the port. That being said I haven't shot the Turbo K so I cant compare them. But my vote would be Surefire.

Redacted

So my Scar 17 killed my ATPIAL C this weekend.... will I be kicked off the island if I replaced it with a MAWL C1+?

You should be alright, I'm pretty sure I've seen Mawls floating on some issued rifles in this thread. I'll try to dig them up.

DOM on the Peq?
Scar killed both illuminator and Ir? Crazy man. I'm hoping I can at least get a year plus of use out of mine.

I’ve seen PJ’s with MAWLS.

Fuck SCAR’s.

Jan 19

Killed everything deader than a door nail.  I thought I had a battery issue, but batteries were good from multiple lots.
I contacted L3 this morning to see about sending it in for repair.

Cool, I hope some pics show up of CQBRs with mawls

Thank you Thanos for the replies and for killing off half of the population.

Now, based on looking at pictures in this thread, I see mostly SF RC2s here. Not sure what the other can is with the hole punch all over it.
But damn it, it's about $1200 with the damn tax stamp!!!!!!!!!!!!