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

Fed one of the CQBR’s some steel case today.  Perfect 72 degree fall day.  Couple observations.  First range trip with this rifle after installing the KAC ambi safety.  I of course installed the scalloped right lever.  Well, I noticed after shooting that the scalloped lever had broken.  It was still on but the flat surface that bolts to the shaft had partially broken off.  Obviously I’ll be calling KAC on Monday....

I also had my Colt 6945 with today and it has a closed tine warcomp on it.  I noticed that the marks on the blast baffle of my SOCOM mini were all gone after shooting.  Couldn’t see a thing.  However there are now little circles on the mounting surface inside the can that coincide with the holes in the warcomp.  Not sure how I feel about that.....

This year I got an airsoft Casv and just recently an afg. It was clearly airsoft. They even took something hot to the writing on the underside to obscure it. Thankfully both parties made good when shown the obvious flaws.

Today was a perfect day for shooting. I had too much around the house to do though. Too bad the range closes in ten minutes.  That's really strange about your ambi safety. Did u get it direct from Kac or op. parts?

Damn well that's good on their part, anytime I've bought a fake I got completely screwed out of it.

Got it from AIM Surplus and it came in legit KAC packaging.  Not my first one but the first problem.  I’m sure they will fix it.

I also learned how easy it is to shoulder bump with a Geissele SD3G today....  There’s one in the Colt.  I’m running the heavy spring if it matters.  3 round bursts were ridiculously easy and very fast after the first accidental one.......

ETA - if you zoom in on the selector you can see how it broke.  I’ll have to snap a better pic.

Hmm, I've never unintentionally bumped with my S3Gs from the shoulder (never tried an SD3G). I've done it plenty of times when zeroing or otherwise shooting from a table - usually a 2rd burst. It's funny when you're trying to carefully zero and then suddenly burst two rounds - sometimes fast enough to drill them practically into the same hole. Annoying, yet strangely satisfying, lol.

ETA: I use the light springs in all of them (3.5lbs or whatever it is). It usually happens when I'm trying to stage the trigger to the absolute last moment before it breaks, and then the recoil carries it right back into my finger.

That’s pretty much what happened to me.  Staged it and must not have had the rifle tight against my shoulder.  Brrrrrrtttt...  After that it was just stage it a bit and pull forward a little with my left arm.  Reminded me of my RR M16 days, just a WHOLE lot less money.

Eh, it's the weekend so he could be busy doing shit.

So this was my week for stamps! Found out that the ATF approved my first packet for my SOCOM despite them telling me the serial number wasn't even in the system or processing. Now I just get to fight for my 2nd $200 check back. But I don't even care right now because we had a great day at the range.
zero rounds down the pipe.


After about 200 rounds. I'm actually surprised at how little she wore. Cleanest one I've ever seen after a few hundred rounds. I didn't take a "final day" pic but nothing much different after 500 rds from the pic below.

Just posted this one's big brother in the block I thread.

Not really but they're very similar.

Nice rig!

Life is good

Pics after FA and dust cover installation on the colt diemaco upper, Geissele airborne ch, early run pre-airborne markings.

And black unmarked 99051 and Surefire m600df

Currently sitting on colt lower in pistol form.

You might already be aware, but just in case... I'd keep a close eye on those teardrop FAs you bought. Multiple people reported issues with the cap just flying off during normal shooting, leaving the pawl and everything else free floating in the upper. I'd suspect that the roll pin to secure the cap was either never installed at the factory or was out of spec. Hopefully, it's no longer an issue.

Although it was double the price, I decided to go Colt for the FA on the two stripped raised "C" uppers I picked up (AU has them for $21.95 shipped). I did momentarily consider how the Mod 0 would look with a teardrop, however ;p.

I swear I don’t need a teardrop on my Mod 0......

If it's a roll pin issue I'll take a look and see how snug it is. I found a colt teardrop fa but it was like $75. More of a retro crowd thing. I usually don't go cheap on parts, but I thought how bad can mess up on a forward assisT. I've had one on my b1 for about 6months now without issue. Though I never really use the fa except sometimes to ensure the bolt fully seats after a malfunction clear, I definitely don't want a defective one causing a malfunction.

So, I had the day off work today, and you know what that means... Time for tinkering. I swear I'll never make up my mind.  Anyway, at risk of sounding really dumb, yet again, the illustration of the mod 1 that milspec posted a page or two ago kept popping into my mind. So I set my accessoreis up to mirror the image (roughly) and it actually works better, for me at least, to run the dual switch on the side behind the light. I really disliked having the the dual pad on the 9oclock position and 12oclock was even worse. I've found by having it behind the afg and light, I can switch my grip and have the ability to access both buttons on the momentary switch and it's comfortable. Thanks for the inspiration milspec. Now I just gotta steal the Cqd vfg from my block 1.



It's very hard to hold a heavy ass mod1 and take a picture at the same time, but you get the idea. This positioning also frees up the grip area when running with the afg. My grip is more solid now by not not havin the dual swith up front.  I can see the counter point being that it is further away and requires a change in gripping method.  I'll have to run it this way for a while before I really decide if it's beneficial in any other ways than alleviating clutter, allowing both buttons to be pressed simultaneously, and improving my purchase on the afg/rail.


@krdt, looks like we got another. Introducing- CQBR opossum. This little dude likes to scamper around my yard foraging for grubs and whatnot. Whenever I'm on my back porch flipping through arfcom, he shows up.

AU has raised C stripped uppers for $21.95 shipped?

Oh, the uppers are free with the purchase of the Colt forward assist. Didn't ya know? ;p.

I'm gonna look into those fa's though. In a moment o generosity I sent the one from my mod0/ block1 as a freebie along with a trade to another member. I do like the amount of surface area the teardrop has, plus I like the earlier block2 builds. I thought it within the realm of possibility, and may even remember a pic posted from CD of a b2 with a teardrop in it.

did you get the uppers from the EE?

How does one tell the difference between a Colt teardrop and another manufacturer?  I have an upper with one installed and was told it was Colt, but don't know how to tell.

dyel bro?

Picked up my Socom RC today.  Got the call Friday, so it made for a long weekend...

Nice! I got the call for my RC on Friday also, and picked it up same day. Now I just gotta take some time off from work.....

I snagged #3 this morning. Factory finish on the dust cover and FA have worn/faded to basically nothing (or never applied ). I kinda like that contrasting tone.

Attached File

I had to evict an o-possum the other day. We've been having a momma and kitten that's been hanging out on the porch, so I dropped them some food one day. I heard something one night and caught that ugly fucker eating their food. I set up the live trap and snagged his ass. Was going to pop him, but didn't have a way to dispose of it so I let him out in a corn field about 20 miles from the house.

I put more food out for them a few nights later. Heard something so I went to see if they were eating. This time a damn coon was eating it. We've literally never had any animals show up before, now it's like the damn Ark.

I hate AU but I'd spend some good money if that were true.

Attached File

Nice looking stick, Conner.

In working with Knights on the replacement I took a better picture of the broken ambi safety lever:



Figured you guys might want to see how it failed.  As said it still worked but for the price I want it replaced.

ETA - Knights has been very helpful and is taking care of me.  First time I've ever had to deal with them for a repair/replacement.

That's a strange way to break.  Def looks like a manufacturing flaw.  I run the same one on my block 1.  Has always felt solid.

Installed a M4QD today!

Attached File

Nah, got them from a retailer. They were supposedly DOD contract overruns. During Labor Day they were on sale at $69 each, with the free shipping over $100. So, I bought two. At that price per upper, you're in Shark Arms territory once you outfit it with Colt stuff. Not terrible.

The dealer has since nearly doubled the price and they are out of stock :\.

Has there been any pictures of a MK18 Mod 0 with the Surefire SOCOM 556-RC? Or is that can pretty much on the Block II CQBR?

My Completed DD MK18 Pistol ("Firearm").

Needs more form 4

Working on it. :)

As far as how to actually post a image on this forum.......

Needs more than that.  See page one.

You need to post the direct image link, not the imgur link. You can right-click the image from the imgur page and select "copy image address" or "open image in a new tab" and it will open to the direct link. That would be:

https://i.imgur.com/qHHlhj2.jpg

Needs more clone ;p.

I can't figure it out.

Does it have to be a certain size?

When viewed from the top, the Colt will have a rolled edge. The aftermarket teardrops are flat across the face and have sharp edges.

https://www.ar15.com/forums/ar-15/Colt_Tear_Drop_Forward_Assist_Parts/123-620537/

An old retro forum post, has a decent pic of the teardrops.

? Not sure I understand. I'm a little slow.
Woo woo! I'm on the edge of droppin some coin now. I'm leaning towards an nt4 I've got my eye on, but that $695 or whatever it is Surefire socom sb is hard to pass up.
I looked at that same upper for a while. Very glad you got it! Bi tone is sweet.
When people put cat food out for stray cats, 90% of that food gets eaten by coons, possums, and skunks. Once saw where a town got overran with skunks and one guy figured out they were thriving off food meant for stray cats. See now, I woulda kept the possum around at sent the damn cats off to the shelter. Possums are more beneficial in my yard. I'm tired of keepin my dog from eating stray cat shit!  Not to mention no one around here understands the concept of spaying or neutering, so I've had a sleepless night or 10  because of cats in heat. Way more annoying than a possum in my book.  I've had cats as pets and at this point, I'd take a possum over a cat.

No, a certain size isn't important. Once you have the direct link, you click the "image icon" when creating the post, paste the link into it and you end up with [ img ]https://i.imgur.com/qHHlhj2.jpg[ /img ] (without the spaces).

You will need 50 posts before it will display without member approval.

Heads up, I posted a mint comp m2 and ml3 in the EE today if anyone is lookin. Obo on both my friends.

Which do you guys like for a build?  DD mk18 socom 10.3" or LMT cqb 10.5"?

https://www.brownells.com/rifle-parts/receiver-parts/receivers/upper-receivers/ar-15-cqb-upper-receivers-5-56-picatinny-prod122615.aspx

https://www.brownells.com/rifle-parts/receiver-parts/receivers/upper-receivers/mk18-stripped-socom-upper-receiver-w-handguard-only-sku100018030-81194-168713.aspx

LMT makes a nice upper but 10.3”.....

This.

I'm not a true cloner or anything but it annoys me to no end when people call their short guns a mk18.

Some guy on YouTube did a 11.5" (or something like that) aero precision build. All aero parts.

"Check out my mk18"

It's like the Daniel defense "mk12" abortion