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

I've seriously considered it, but have no idea who I'd pay to do it or if it'd even look correct.

Surely there is someone in this thread that could get close ups of one?  I think getting it engraved would be the easy part.

That would be awesome!!! I would be in!!

Yeah, I've seen some pretty decent pics of it.  I'm not all that familiar with the process (at least the Eotech process), that's why I'm a bit lost on who I'd have do the work.  I mean, my SBR lower was "laser engraved" but that shit goes pretty deep.

If you have an idea on who could do it, I'd definitely be in.

ETA:  Pretty decent pic.  Disregard wrong one.

I prefer the clone stamp tool.... its like a ghost gun that way!  

(not 100% cqbr clone, but posting to reference hiding S/N from photos)

For those asking about the SF Mini Monster suppressor I'll ask the detachment tomorrow if how they got issued them. (SOCOM or State funds).  Seems they do have some leaway as their M4A1 have different rail (Samson IIRC) and some are equipped with SF 3 prong FH.  I've replaced several KAC QDSS FH (N4T) with proper SF FMSBC FH (4 prong) on their 14.5" guns.  Just finished T/Iing some of their sniper rifles (2ea x M107 .50 BMGs, 1 x M110 7.62mm and 1 x XM2010 .300 WM)


CD

Thanks CD, I just need a reason to buy one

 

You have an awesome job, CD. And thanks for all of the info you post in here.

PS- Did you ever pull a rotation as an SSGL at Buehring? Around 2012? That would be strange coincidence if you have.

So was the SF Mini Monster for a 14.5" or 10.3" URG?

 

Negative, 2012 was one of the very few years that I didn't have use my passport at all.  Stayed in good ol' USA!


CD

I'll ask them tomorrow.  They keep the lower with both uppers, suppressors and their pistols (M9 and G19) all in the same Pelican/Strom case.

CD

Ah. The reason I ask is that I was there briefly in 2012 and met a diver that was working at the schoolhouse and knew his shit about all types of small arms. For a moment I thought you may have been one and the same.

CD - those are cool pics man.

Really sweet to see some of the random stuff that shows up like the mini-monster.

I don't feel as bad having the 3 prong now.

What rear sight is that?  It looks slightly different than the LMT L8A I purchased last night. Did I get the wrong sight?

 
Yeah,  it kind of falls into the "as issued"  category now.


There has been some really good information hitting this thread in the past few weeks. I've been updating my spreadsheet like a mad man. Btw,  if anyone sees and discrepancies with it, please let me know.  I'd like to make it as accurate as possible.

Thanks CD.  You are the man!  I "might" be ordering a Mini Monster later today.......

And, as another poster said, I don't feel as bad about my three-prong's now.  My brakes are still verboten though......

It was a Colt carry handle that I cut with a Dremel... the gun was stolen so if you see the rear sight, you can have it... just bring me the rest of the gun... and the head of the dude that was holding it.

I remember that thread. They got the MP5 too, right?

I am so sorry for your loss.

wait...  WHAT?  I must have missed this thread you speak of.  Link?

Have a good friend that just got a $50k fiber laser engraver.  Get me the info and I can make it happen.

Yes. They stole my car and got BOTH of these:
" />

Universal BG checks wont stop that.....

Jus sayin...

I guess it wasn't a thread, because I can't find it. Did you post that info in here? I can't remember where I read it.

ETA: As a grown man- I would cry if that happened to me.

Wow, I'd like to read the thread about it so I don't derail this one...  Couldn't find it though.

Hoping someone can hop in with close up pics of markings.

They're no different than the ones on the 553s.

It looks relatively the same, but the lettering lines up differently.

How does one go about knowing what the actual code reads?

Found a blown up version of that photo and was able to crop out the Eotech for a little clearer view.

It's going to have to be higher too since the commercial ones have the military/law enforcement use where it's placed on the mil ones.

Doesn't the current "for law enforcement/military use" marking get in the way of doing the SU markings?

Valid point.  Unless we can get some tan hoods without the LE marking (doubt that's even possible), I'd say we're probably SOL.

I don't think it would be too hard to have the anodizing stripped.

Maybe that would be enough to remove the commercial mil/law enforcement lettering, then get it re-anodized and then laser engraved?

removing the coating may also remove the L3 EoTech branding at the top that would need to be removed also.

I'm all for trying this just to be different.

I need to get an exps3 first probably...

Yes I posted it here in this thread somewhere. I didn't cry because I knew insurance would cover it. It was stolen from a fancy hotel's valet lot. They let a homeless 23yo walk up to the valet lock box (which they had left wide open) and the guy just plucked a key from the unlocked box. It was all caught on the hotel's own security camera. The hotel's head of security SWORE that he reviewed the tapes up and down and NEVER saw ANYONE walk to that lock box. One of the local police officers (a guy who worked part time at a gun store for 'fun') took it upon himself to go review the tape and, low and behold, CLEAR AS DAY there was video of the guy stealing my key from the box.... I guess the head of security *missed* that part.

They caught the guy about 3 hours after he stole my car. He was asleep in the back seat, wearing my sport jacket, with my Glock 19 tucked into his pants. All of my guns and cameras ($30k worth) were gone and he wasn't talking. Still hasn't.  

Some light block sanding of the sides would fix that. I'd bet Victor at US Anodizing could duplicate the color of the orginal anodizing.

Had anyone ever tried to buy a SU marked unit from L3 when they were doing direct sales?

true true...  Light sanding may even remove the lettering and leave the gold finish too.  I wish there was a way to get a replacement hood for an exps3 to mess with like there is for the 553s.

Edit, just scored a tan exps3 hood!

Your google-fu is weak. link Should be able to get them direct from EOTech I'd assume as well.

Not weak, I tried calling them, they don't offer them for sale directly for the exps-3.  They said lonestartactical has the replacement hoods in black, but you have to call them.

I guess the black wouldn't matter too much if it was getting reanodized.

At any rate, I scored a gold one.

Found this on page 83 of the old thread that was posted back in 2011. Post by a member named avex. I had to save it to my photobucket.

https://www.ar15.com/forums/t_3_118/408319_SBR_picture_and_discussion_thread.html&page=83

Nice

They're out there. The clone game just stepped up a notch.

Managed to ask couple of the team members during dinner about the Mini.  Seems they showed up to the team room about a year ago.  The SF SOCOM was issued with the 10.3" URG and the KAC with the 14.5" M4A1.  I'm guessing bought with State or unit funds (same with the SF 3 prong FH) but I'll keep digging.  Got a range Friday with them and we'll put some rounds down thru them (along with some more 84mm Carl Gustav and Javaline's )  Might be taking out the Mk44 minigun also.


CD

(back in 04-05', 5th SFGA bought some ARMS 50C forearms as we couldn't get KAC forearms at the time.  We also had bunch of C-More Red Dots on unit funds)

I remember when we got the Carl Gustavs downrange. I remember it was a big deal since we where the first conventional force it get them. Very cool. We only shot a couple at the range though.

That looked more or less insane to me.

If you guys recall, there were 2 pics of a guy kneeling on the ground and we all thought it was a Mk 18 FSP rail. I think we figured out it wasn't, but for some reason I remember there being a black mini monster on that rifle.

And then there's that other weird pic of the Block II with the black mini and the black XPS.

So it seems like some random SOCOM can models have ended up floating around somehow.

It's interesting to hear about the 3 prong. I wonder what the deal is with that. Like if someone actually wanted it because it's a better flash suppressor and/or it's different/cooler than all the standard 4 prongs or if it just came with the can or something.

I don't feel so much like I went overboard with an order of 10...even though I accidentally left out my LMT MWSE.

I'd bet there will be another run when word spreads outside of the clone forums and as we need more...or forgot one the first time.

I'm probably talking out of my ass, but that group may not have not have access to Surefire cans yet state side and bought their own mounts and even a couple of cans to use overseas. They would also then have access to SOCOM RCs overseas and they wouldn't have to worry about mounts. Could be totally wrong.

Do the bottom of the EXPS3s have the UID/whatever it's called label code on the bottom?  So if one were to get laser engraver access, they could replicate the code from the bottom so it would read correctly?

Edit:  I guess what I meant to ask was are the markings on the bottom, the same as what should be engraved on the side?