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

Holy shizznit batman. Ill take 10 of them bitches plz & thx

Got my BRT .070 gas port insert installed last night in the Mod 0. If you've ever wondered if getting an FSB off a painted barrel is a pain in the ass: yes, yes it kinda is. Suppose I'll have to repaint forward of the RAS at some point. Anyway, I haven't shot it yet, but I'm definitely looking forward to trying it out next week sometime. Hopefully it'll finally shoot as soft - maybe even softer - than the CQBR :D.

For anyone curious, I measured while I had it apart and the stock Noveske N4 10.5 gas port is right around .080. Kinda annoyed that the Noveske CS rep basically misled me. I called them before I decided to purchase to ask about the gas port size, and while they claimed the info was "proprietary", I asked was it closer to Crane spec .070 or DD .082 and he indicated it was closer to Crane. I also specifically asked, "I know you can't say outright, but it's nothing huge like the DD .082 port, right?" and he said, "Oh, no, no."

Sounds like he probably had no clue the size and instead just agreed with whatever he thought I wanted to hear. I would've preferred he just said he didn't know, but whatta-ya-gonna-do?

A few pics:

.080 vs .070... funny the difference .01 can make:


Drilling out the gas port between the barrel and gas tube:


Getting ready to drill the FSB base between the sling swivel ears to clear the tap body:


Tapping the port for the insert:


Insert installed and being test fit for gas tube clearance:


Test fitting FSB for barrel clearance, all is GTG:


The Magpul BEV block makes a very passable FSB block as well ;p.


All done save for reinstalling the RAS and optic :D.

Save one for me.

Well done

I don't know how that post turned into a mini installation guide. I originally was just going to post the .080 to .070 comparison and the shot of the insert installed, but then I started going through all the pictures I took and things took a turn, lol.

Thanks again for the heads up on all this. I was able to cancel my order on the light (got a confirmation back almost immediately) and place a new order with IWC for $219 shipped. You just brought down my cost to $348.78 at this point. I'll follow-up with Optics Planet tomorrow about the switch and tail cap combo. I actually did see that one before I pulled the trigger, but noticed one of the CS reps had replied to a question about compatibility with the Mini Scout; saying it required a different part. It definitely looked the same, so good to know it works fine.

Maybe I'm crazy, but I've been getting my SR07s from Amazon for $30 shipped.

You sure you're not thinking of the ST07? Only SR07 I can find on Amazon is $97.

https://www.amazon.com/Mil-Spec-Activation-Platform-Scoutlight-WeaponLights/dp/B001V2P8X0/ref=sr_1_1?s=sporting-goods&ie=UTF8&qid=1520812058&sr=1-1&keywords=sr07

But then I'd need 11.....

That shits tempting tho. One day I will be made of money, and one day I will send you one. It may take a while but you know I come through in the end.

I'm considering getting  a used eotech 'n' cell 511. Is $250 reasonable?

I would say thats the max I'd pay. I would try to be at 200 tho

Supposedly the tan M300Cs are a limited run, so you might want to start with one and go from there before they're all gone ;p.

Mmm, 500 lumens of Surefire lighty goodness and almost 2oz lighter than the M600 you have now at 200 lumens. *whispers* Do it... doooo it.

Ok....grab 11 then.

Thank you. I know more about aimpoints than eotechs, but thought the price seemed good but wanted to be sure since I don't know much about their used prices.

I'll see myself out....

Lol... for a brief moment I hoped you'd found the pressure switch promised land. A fabled land where a man can drink his fill and buy pressure switches for 65% off :p.

A place where you can find insight dual switches for nothing. A place where they make streamlight dual switches.

A place with room to roam and tailcaps are included for free. A place where a man can put his feet up and dream big dreams... where Insight dual switches are available with plugs for both Surefire and Insight devices. A place... okay, I'm done now, lol.

You all are not good influences for my wallet. have these two builds off to a good start. Getting them sighted in while I save for the other accessories.

Anyone have a KAC 99051 Taupe front sight they would sell? looking for one of the darker chocolate brown sights. Thanks.

It was motivational.  Made me want to wail on taper pins

There are a considerable amount of things in this world that give me a chub. One of them is that FSP 14.5, and another is that block 2 CQBR.

I bought one of those IWC M300C's - good deal but be prepared to wait, took almost two weeks to get it.  I guess that's not the end of the world but when your used to 2 or 3 day shipping these days waiting that long was annoying lol.

I also found at my LGS an lightly used original M300 Tan the same day my M300C arrived, and I believe I prefer the original.  Sure the new one is 500 vs 300, but the 300 actually seems to light up better/more natural.  The 500 is just kind of a small spot of bright light, while the 300 opens up a bit more and not as "white".  Plus the older one is not all jackson pollack tan lol.  Anyway the older one I put on my BKII, the newer one I guess I'll use on my Mk18's or something.  I also have a black M600 I use on my "standard" run of the mill BCM/Centurian setup AR as well.  Or, maybe I swap the 600 and new one around, 600 probably better for the longer MK12's.

Anyway there's a good thread on the differences here - AR15.com thread on 500 vs 300 M300 -    But I think it might just boil down to inside old version is better/outside new version is better, generally speaking.

Original Tan


New 500 Lumen Tan


M600

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14.5 FSB & MK18

Can somebody please repost the picture from the first page of the topic

"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."

Probably these. One of my favorite setups. I have one with a FF RAS

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Yes, thank you! Wow a1 lowers

My post count is still too low to embed pictures I think but I updated a little bit here. Got the Colt upper on there now and in the long wait for the SBR stamp to come back...hard enough in Illinois as it is, lol. Need to decide on a flashlight...liking the Surefires but not sure how common they are.

Always been a fan of that set of pictures.

Me too. I think these are a couple more

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Block 2 accessories on a block 1 is most excellent.

Here you go.

Those are really cool, I don't think I've ever seen that set up before....thanks to everyone who posted.

Seal Team 4 member...

Need to hit the range.  Shown with two Mk16 SCAR mags loaded with Mk262 Mod 1 77gr OTM.  Scope is off a RCL here

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CD

I love the look of non issued issued parts on Sopmod guns.  Also now I don't feel so bad rocking an ECOS calibrated for a 14.5 gun on my 10.3.

Whos the manufacturer of that scope?  How is the eye relief on that thing?

Its a Swedish manufacture I believe.  Scope been in SF inventory since the early 90s, just not part of the SOPMOD program.  Eye relief is short.

CD

Need more pics and more details of that optic.

It is speaking to me.

Might look slick on a Mod 0 style MK18/CQBR with B.E.Meyers or NT4 mount.

3x

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CD

I thought that thing looked familiar, yet very out of place

That makes it even cooler in my book

Love this rifle. My favorite build for sure. Where are you guys finding good deals on the exps 3-0? Is like to put the correct eotech on her. If anybody has a lead on a tan, Msg or tag me thanks.
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Who knew there was grass in the middle of the desert of az
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I was curious about the ti-7 stock. Have these been spotted in the wild like vltor IMODs or magpul ctr's? Any itw pics around? And what are your thoughts on it/ how does it compare to a b5 or lmt sopmod? Ex. Length of pull, angle of cheek rest, weight...etc. thank u in advance.

Pretty sure that's the stock @Stukas87 used on his issued CQBR. If it is the same one he likes it, and it looks like a good stock to me. Sure does look a bit funky but....that doesn't really matter in the end.

I have the B5, the LMT sopmod, and that stock above.  It's amazing.  By far on par or better than the aforementioned.  I'd post pics but photo buckets sucks cocks now and I'm lazy.  Do it.

Ah hell, that was less than helpful.  Here.

^Nice. That coyote has an orange hue to it. The price point isn't bad either ($70). I may check one out to see how it feels. Thank you.