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

Found mine on the EE for $185...and I like it!!! Attached File

looks like i jumped on this wagon before the prices go nutso. people are scooping them up fast...last batch at G man came in a week ago and are already gone. seems like KAC rails

Finally added some brown laundry bag accents like I usually do. Camo so good you can barely see it.

It has become one with the pillow fort! ;p

Looks awesome... I like the laundry bag accents.

The mail lady came bearing gifts today :D. Got my new Raptor-SD in FDE and it looks pretty damn spiff. Only had a chance to palm rack it a few times to test it out, but so far I love it - a lot more solid feeling than the GB. There is almost zero distortion or sideways play when blading it, whereas the GB gets a little bendy and feels a bit rickety. The SD model is machined off square behind the fancy vents and fits very tight inside the receiver channel. No idea how it will compare to the GB when it comes to gas blowback, but the theory seems sound enough. I'll put a few hundred rounds through it this weekend and see how things go.

Very interested in how the SD compares to the GB...

Swapped out my black scout for a tan m300c. Bump up in lumens and a step closer to the tan master race. Just in need of a tan tailcap, damn my OCD.

@STL_Nik Looks like youre on the wrong side of the river, you cant have anything fun over there anyway

edit: Needs MOAR pics...

Here is my use for a DDC  mk8



And my block 2 upper...

What state are you in? Can’t remember where I mailed that Colt stuff...

*undisclosed location in Mexico*

I am willing to trade you a tan Scout tapeswitch tailcap for your black one. I even have a WTT ad posted in the EE. IM me know if interested

literally waiting on my adj gas block in the mail, but i am currently here and that is ok

Can someone point me in the direction of a Colt Fire Control Group?

https://www.ar15.com/forums/Equipment-Exchange/Colt-new-takeoff-parts-FCG-buttstock-selector-tube-/125-1729200/

I believe SharkArms has some. You'll just need to email him and see if they are in stock.
https://www.sharkarms.com

How do you feel about the light output from that new m300?  I passed on it because I heard people were sending them back because the light on the older 300 lumen m300 was better and they didn’t like the wash and color of the new one...

Lately, I've been having the occasional dirty and blasphemous thought: should I shave the FSB and put an Mk8 on my Mod 0? From the AP/Wilcox and paint, it looks like you did something similar to that, lol.

Only thing that stops me is that I don't really want my collection to be without a Mod 0. That, and I figure I'd have to buy new optics (something BII just seems proper, like an EXPS3) - at that point I might as well turn it into a separate build. If you scavenged your Mk18 to build that... bold move.

I think it's overblown. Was I a little disappointed they didn't keep the same spill/throw as the 300 lumen model and just up the lumens? Yeah... but, if you want a tan Surefire, it's really not that big of deal. Basically, if you already have a 300 lumen black M300 and/or you don't care about the color, there is absolutely no reason to buy the 500 lumen model. There are new or barely used 300 lumen black M300Cs out there for a lot less. On the other hand, if you want it for the almighty tan, it's perfectly fine. If you missed it, I posted a beam comparison a few pages back when I first received mine. There is a difference, and I slightly prefer the older beam, but it's not remotely something I would send it back over.

I think people are comparing them purely to the 300 lumen model as in "is it worth it to upgrade" versus "do you want tan". I would've swapped out my 300 lumen black for a 300 lumen tan without the lumen upgrade, but if I were buying the new one purely for the lumen bump, I'd probably be disappointed, too.

@Stl_nik

Palmetto State Armory.

I totally made this one of my profile pictures...

LOL!

1hr ago i chopped my FSB and made it adjustable.

#scavenged
#originalmodelnewparts
#caughtredhanded


<a href="https://postimg.org/image/4d2u6q4vf/"></a>

This makes me want to cash in my WMX200 for a tan surfire

I'd love to have a WMX200 but I don't think I could make myself pay over $500 for one, much less $1,000.

Been a long time since I've posted this greasy bitch. Debating whether or not to get a SOCOM556RC for it.

Do it! $695 @ AU

Surefire 556RC

At that price the question isn't should you buy a SOCOM RC, the question is how many should you buy, lol. If I had the extra scratch I would buy a second one.

I'd have probably bought two by now if we could have suppressors here.  

I know I'm going to regret not buying another one at that price, too. I'm already teetering on the brink of fully committing to a G rail 10.3 build and I'm sure I'll end up wanting another RC for that. Hell, I have most of the parts already from CQBR cast offs: Spike's lower, DD upper, a spare Colt BCG and now an extra FDE Gas Buster. Add a 10.3, S3G and an Mk8 and I'd be in business. Starting to wish I hadn't sold my extra KAC taupe 99051 and Surefire M300C :\.

It's a vicious cycle.

We can have SBR's just need a C&R FFL to meet Illinois restriction that only "Collectors" can have SBR's.  We're working on suppressors.  I need out of this state but until my kid is 18 or my ex wife dies, I'm stuck here.

Can someone recommend a CHF 10.3-10.5" barrel for my next build, appreciated.  TIA

The current DD 10.3" with .070 gas port is your best bet IMO. New DD 10.3s show up in the EE fairly often at good prices from people parting out Mk18 SOCOM URGs. Otherwise, BA just released a CHF 10.3", but I'm not certain the gas port size.

Something is off with the M4A1...



Gearing up for a coyote hunt tomorrow night. About to freeze my ass off.

You can pick one up from PSA assuming they still have them in stock.

You could buy many SF for what a WMX would fetch.

I'm low-key happy that we can't.

I saw this a few weeks ago.
Thought it over, and said, nah, not now...
But that price...
I had to.
You all made me do it.
Just placed the order for a tan RC 2 minutes ago.
My first can!

Ha. It is kind of nice not having to worry about suppressing all the things.

I’m doing everything I can to hold off...I know it’s not clone correct but I think a Saker ASR 5.56K and/or SpecWar 5.56K is going to be my first...but then there is that tan RC staring me in the face...dang it!

You can pick up the tan ones now again that surefire is cranking them out for a little over the 200 mark. Impact weapon components has them and surefire has them. I paid 220$ shipped

Aren't there some pics of 7SFG Mk18s with tan Mk8 rails?

Yeah, I got mine for $221 shipped from Surefire. It would've been $209, but Surefire charged me tax for being in AZ. I'm just saying if tan isn't really important to you, it probably makes more sense to grab a black 300 lumen for $175-$190 and save the extra cash. I just don't think the 500 lumen is much of an improvement over the 300 unless you're wanting a tan SF.

I would agree that there really isn’t that much of a difference. The 300 lumen model seems like there is less spill/splash.

Attached File


So this just happened. Bought a KAC RIS. Don't know why. I guess I'm building a MK 18 Mod 0 now. Is the RIS a desirable rail? Kind of regret buying it.

You dun messed up sir. Send to me for proper disposal.

(Yes the KAC M4 RIS is a desirable rail, and I would not regret buying it) I miss mine quite a bit. Its a fairly historic rail in the "hardcore clone game" god I sound like a douche saying that.

I keep a RIS on my early Block I M4rgy.  First rail I was issued back in the 90s.

CD

I’m starting my first clone build ever. I have the following:

-Colt 6920 oem 2
-DD factory Mk18 fde upper

Should i use the DD barrel with pinned LP gas block or should I get the colt cut down to 10.3 with the shaved FSB?  The hand guard should fit over the factory shaved down FSB correct?

I also have a KAC rear and taupe front and a tan Surefire M300 (closer to the tan master race lol). I figure I will steal my TA31 from another rifle until I can get the optic figured out.

Thanks in advance for the help.

RIS isn't very mainstream.  You don't want that.  I'll gladly trade you one of my RAS for it.

Correct would be the 6920 barrel cut down and a Mk12 gas block. Not correct, just stick with the pinned DD barrel.

I feel your pain. I did the same thing yesterday with this thing. Got home and was like, what am I gonna do with this? I feel better knowing I’m not the only one that does that




Guess I’m building a mod 0