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

An H2 would be more reliable between the two, but you can probably get away with an H3 for a softer recoil impulse - even with an .070 port. I use a 5.43oz H3 with my .070 unsuppressed and it's super soft shooting. I even went so far as to try a Sprinco Blue with the H3 and it worked perfectly for me over 280 rounds. That setup had practically no recoil at all; it actually felt a little odd to shoot because the cycle was so slow. Unfortunately, everyone else that shot it in that config had a failure to lock back on empty - also one or two short strokes :\.

Figured it was just cutting it too close for reliability and now I've settled on an H3 with a standard Colt carbine spring. I've put 840 rounds through it since I swapped to an H3 and I've yet to have a malfunction either myself or with anyone else shooting it. Technically I suppose it's 1,120 if I count the H3 using a Sprinco Blue, but I don't count those because others had malfunctions.

ETA: Top o' teh page.

Freedom intensifies.
With the exception of Websters Parachute Infantry, all the hard copies are signed by the respective veterans, most first editition, first print.
Tonight We Die As Men is near and dear to my heart.
Yes, book nerd as well as cloner.

Very nice. No copy of Rogue Warrior? I thought it was a pretty good read - the rest of the fiction books, less so.

Definitely going to have to check out 'With The Old Breed', I've never read it.

10/4. I'll do several rounds with my H2 and see what happens, worst case I'll buy an H3 and throw it in to go. I think suppressed an H2 should be more than enough

If you don't want to buy a whole new buffer and like to tinker, you can change the weights out yourself.

Is KAK the best place to get buffers? Just bent my snap on roll pin punch that fits the buffer changing to the a1 FA today so replace before thats done

Yep, this is really the way to go. I bought a handful of tungsten weights from KAK; also Damage Industries during their 50% off sales can be a good option for getting inexpensive buffers/weights to scavenge for parts, but their prices seem to be creeping up. Weight wise, you only need 3 tungsten weights and 2 steel weights to make H1 - H3.

You gonna try and tell me you don't have Lone Survivor, The Warrior Elite, The Finishing School, The Mission: The Men and Me, Kill Bin Laden, and Not a Good Day to Die?

IIRC the number tells you how many tungsten weights you use: H1: 1T 2S, H2: 2T 1 S, H3: 3T 0S.

Or No Easy Day?

Lol, yeah, I don't even have that one either.

It and LS are the only ones I've got.

All I have is With the Old Breed and American Sniper. Other than that, just a bunch of welding books.

So fresh and so clean clean

That top one makes my wrenis tingle. Not to say the bottom one doesnt, but dat 230 and corn cob doe

Forgot I've got AS as well...somewhere.

I'd love to have some welding books. Been thinking of using up my GI Bill for some welding certs.

Those are awesome setups.

We can prob work a deal out on em sometime if you want em. I have enough hands on experience that I don't think I'd really need the books anymore. But they were Purdy expensive brand new. Fucking college.

Pre M600 and brown laundry bag accents-

I'm more than good enough for the work I do now. Been thinking of a career where I don't have to sling 140 pound brake drums and 200+ pound wheels and tires. Body is going to hell with a quickness.

She's looking purdy. I just started a H build myself. Can't wait to put some wear on her.

Jeebus. You working on big rigs? Very nice on the Holland.

I just went full retard on the effects. Looks fucking ridiculous.

Yup, big rigs, trailers, some earth moving equipment, plows.

I would definitely pursue something else.

The worst part for welding was just contorting my fucked up back into fucked up positions, burning myself all the fucking time, and arc burn/arc flashing myself. But honestly I think lifting heavy at the gym and motocross has done more damage to my body than welding did. Maybe we should take up something nice and gay like sewing quilts in a Chinese sweat shop.

I like doing it (though I'm more of the shop manager these days ) and they're surprisingly easier to work on than cars. And you can get away with torches and hitting shit with hammers. Parts are just heavy as shit and usually greasy.

Yeh I'd lap that top one up like a dog in a bowl o water.. need moar kac in my life

I do the same things, just with mowers and tractors. Includes all that, minus stupid heavy shit . Plenty of time with hammers, torches, broken tools  etc. Of course sometimes you gotta be toddler sized to fit in places to work on broke things. even sold a snowplow to NSWC recently

Is there a mk18 photo album like there is with the mk12 thread? I want to see as many pictures as possible.

Still looks so what mild on the accents compared to some seen here. My eyes must be goin out cuz I couldn't even see any brown laundry bag accents on the first pic. Could be the pic, ya that's it, I don't need glasses, the world looks better all fuzzy and stuff. Kinda like playboy from the 80's.

What paint did you use on this? I really like the darker coyote brown look opposed to some of the lighter fde paint.

Thanks.

i used Aervoe coyote brown as a base and OD as an overspray.

So much for a photo of the mk18 with the nt4, my dealer is an indoor range that's fucking useless unless the owner is there, which he never is.

Lol the first pic was right before I added the brown. Order of events.

-Painted

-Later added brown laundry bag

-Later swapped M952V for M600C

This pic is right after event 2, but before event 3.-

If someone has a lead on a SU-230, please hit me up.

"send...nudes" ROFL

Now I get it. Today was a sopmod/surefire Sunday for me. Ended up goin the easy route and just painted the damn sopmod. It was such a light coat to begin with that it covered up just fine with a light coat of flat black. And here is my newest m961/962 with surefires z48 tail cap.





Eta- here's the beginnings of my entry into the block ii world.  Got a good deal on a cutdown m4a1 fsp ris ii.  Doubt I'll ever get ahold of a Mk 18 fsp so this'll do till I get a reg mk18 ris ii. I stripped the Cerakote of of if and plan to repaint once I get a std barrel nut wrench again and a dd ris ii barrel nut wrench.

Can anyone school me on SU-231s/SU-231a's?

I know they're just EOTechs, but I assume if they're marked as such they're probably not exactly acquired in great and honorable ways?

Is that the only difference?

Not entirely true.

There are plenty of civilian su231's.  su231a's not so much.  I do know of at least one civilian su231a on the civilian market though.  Eotech internal person.

This. The SU/PEQ marked 553s are abundant and legitimately acquired. The marked EXPS 3-0's, those are a bit different.

Any difference other than the markings?

This northern Indiana winter has finally gotten to me. Did my first attempt at a rattle can snow camo job inspired somewhat inspired by the photo below. Mines obviously not a block ii, but you gotta work with what you got sometimes. After finishing it, I think it needs more dark areas. Feel free to tell me what you think. I kinda like it, though it may head some more work, or just some use now. I Want to paint the lower, but I also wanna keep it black for my mod 0. What I really need is like 5 sbr'd lowers.

Looks good! If you're worried about it being too light, that is definitely going to darken up in the light areas several shades with some use. If snow camo is the goal, I'd wait and see how it looks in a few months.

Thanks. I'm ready to paint my block ii already and I don't even have it finished yet. Once you start, everything looks like it needs rattled up a bit. Tryin to convince myself to leave my mod 0 black is getting harder.

Just go two of everything. One rattled and one black.

Attached File

Nice! That's definitely the (expensive)route I'm headed down. I already get 2 of every optic and accessory as it is.

If you had to pick one to read, which would it be?

If you're looking for a nice wall piece you can order prints of the weapons featured in the Vicker's guides. I have volumes 1 and 2 but volume 2 has some nice block 1 and 2 CQBR information/photos that may be worth picking up.

https://www.vickersguide.com/purchase/custom-print

There's no "preview" but tonight I'll try and share what the CQBR options look like from my book.

Eric has some nice print's too @ https://projektmonark.com/collections/cqbr

Mainly block II stuff though.

Not sure about current ones but was told that the older 231a's had slightly different internals due to being tested for waterproofing at 2 atmospheres (66 feet)

Not sure if it's still that way after all the Eotech updates or if they standardized.  my su231a's all show waterproof to 66 feet in the manuals.

Noice, noice.

I need NV :(. I either need to materialize more money or stop building new guns for a while. I'd need something like a PVS-14 and a full power PEQ15 to get started... so, what, about $5k? I know fuck all about NV.

I just see $5k and think, "That could be a CQBR w/ chopped Mk18 RIS II FSP or URGI/Mk8 10.3 and another SOCOM RC as a cherry on top :\"

Thanks, man!

Yeah, but can you see it in the dark?