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

Thinking the same.  I don't like adding the KAC rail panels on the RAS as it makes it bulky.  But the gun gets very hot doing mag dumps (Govt gun) and forgot my gloves that day.  Thats why I put the oval double heat shields HG on.

550 cord loop around the delta nut.

That was easily the hardest/most frustrating install I've ever done for anything gun related (at least solo)

Really?

Never had an issue with these installs.

Time to track down an RC2.  Met up with another member today to try his out.  Been hesitant to pick up a rifle can until I tried one out.

I got mine a few weeks back... Only put about 80 rounds through it so far.

I need to actually check the POI shift, and repeatability with it, its got that typical lil Surefire wiggle to it.

Pays to have the proper tools. IE vise, block, roll pin holder, punches, hammer and magnet.

Collect parts
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Drive rivet into sling swivel and flatten end
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(after install photo)
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Insert block or STEEL mag into vise at 90 degrees holding rifle up. Could also just clamp barrel in vise. Several ways to accomplish this.  Add clamp thru FSB with swivel able to lay flat towards muzzle. This will allow you to slide on rail panels onto RAS if desired.  

Magnetize roll pin on magnet for roll pin holder to hold (just easier) and drive one roll pin at a time.  Once roll pin holder hits clamp, switch to wider punch and drive half way thru locking bar.

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Finished. Note First Gen locking bar had two curved sides and marked A1/A2 for different barrel diameters. Currently only made for A2 diameter barrel and flat on one side as seen here.
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I still retain option to add RAS
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Good stuff, @Combat_Diver ; thanks. I've got a 14.5 upper with RAS, and I'll have to give it another try some time.

Looking for a Pachymar Vindicator grip, does anyone remember the shop that dropped them about 6 months ago?

Super old news, but I totally forgot to share it here now that the video is released. Back in January I was lucky enough to participate in filming an episode for the massively popular YouTube content creator Mr. Beast. The premise of our segment involved shooting 10,000 rounds from machine guns at a Lamborghini protected behind a barrier of other cars and material. Of course I utilized this opportunity to put some of my clone rifles center stage for the world to see!









The lowers for each of these are Colt M4 stamped transferable receivers. Definitely not mine, but I was grateful to employ them as hosts for this special occasion. Together they are probably worth as much as the supercar we were shooting at.



Course of fire required 300rd strings of burst and mag dumps before swapping out to a second rifle. Guns were allowed to cool while we jammed mags for a second take and then hammered them all over again. Proud to say everything besides our PKM functioned flawlessly. Though I'm sure at least two of mine need new barrels now. I'd never seen gas tubes turn blue!

I wanna see what they looked like after.

Way cool.

I had posted a longer thread in GD if you want to read more behind the scenes. Turns out there were quite a few arfcommers involved in the production.

After the shoot I broke everything down for a deep clean and inspection. The Army SF inspired clone had a FN SOCOM barrel and it held up quite well. One of its gas rings broke inside the carrier but it still kept chugging. The MARSOC and Navy Mk18 builds had government barrels, and welp, those are a completely different color of ugly now. Shame because I had just installed new date-matched Crane cut down 10.3's on them. Still need to see how they group and will report my findings.

AF DAGRE

Apparently  these uppers paired with the cans are called MK18 RAPTR packages.

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Mag dump

Mk18 Mod 1 10.3"

I'm gonna have to pass. I'm not a fan of those huxwurx cans... Due to their aesthetics.

Who the fuck is drinking out of a mason jar (with a metal straw) while in uniform? I couldn't take that person seriously.

Awesome! Thanks for posting. I don't think I would have seen that thread otherwise.

Whisper pickles indeed. And for all of the rah-rah over the next-gen benefits of flow-through, post-T&E I still prefer traditional designs for performance. Get a gas-managing CH and drive on.

I do appreciate those builds though.

Local resident @Tinycrumb gives an in depth history lesson on Surefire socom suppressors

Great video dude!

TinyCrumb on Surefire's SOCOM evolution

That rate of fire is beautiful.

Get less back pressure, get more db. There's no free lunch and you can mitigate over gassing a myriad of ways. I do like seeing the pictures though!

Also less lead exposure and lowers health risks from high round counts. I think socom did a study on it, but can't find the article atm. But it's the reasons we are seeing things like flow through designs and the SURG.

Rifle in top pic, second farthest back on left.....is that a pistol brace? If not, what butt stock?


Edit:

This guy...

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Yes this is from armourer familiarization so who ever hosted, hux probably, probably brought other things with them to show off.

Thanks man. That makes sense.

Had me wondering though.  

Put an upper up for sell in the EE.

https://www.ar15.com/exchange/topicEE.html?t=2434047&f=159&type=1

Since KAK is now clone correct (making barrels) do they make “clone correct” Bcgs also?

Would have to ask KAK if they ever got a Govt contract for them.  @catalyst686

That's a PDW stock. Look them up, there are several of them out there. Some have their own BCG, some are compatible (the latest ones) with existing BCGs.

It's a minimal stock design

After looking again,  it appears that you are correct. I see it now.
Thanks.

It's a SB PDW brace.

Link

It is open in the back to put your arm through. A stock would not be open. It also has a velcro strap around it.

... read above - a brace (less expensive).
PDW stocks are cool as fuck - consider them (I did)

PS great to see you here again bro

Thank you both. Possibly the MAXIM CQB PISTOL: GEN 6 – PDW BRACE ?

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And good to hear from you as well Solo.

The only way to get a su-233 is second hand at this point?

As in used?  Yeah.

Thoroughbred has some surplus ones.  Price isn’t great, but you don’t have to hunt the forums.

https://www.thoroughbredarmco.com/product/1265/

He’s been sitting on these for a while.

Thought so, thanks man, yep saw those, lookin a little too salty for me.

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That dudes shooting into the past

Top rail goes for a swim in 3, 2, 1....

Yeah man wtf

I hope dude isn't responsible for anything important. Lol

can anyone tell me who makes the stock on the fde URGI with Razor lpvo in the front Looks like a Magpul but I'm not 100% sure

Geissele “BF” stock.  Their own in-house design.  No idea if they actually manufacture it or if it’s OEM’d.  Doesn’t appear to be available as an individual component as I’m only seeing it on the GFR rifles currently.



https://geissele.com/geissele-freedom-rifle-gfr-14-5-6arc-luna-black.html

Nah someone has to be messing with this guy right?

"Hey we got some ammo we need to get rid of, go grab a scope from the armory and throw it on this for a photo op"
My best guess anyway.

He's gotta be the most hated/ biggest dickhead in the unit for no one to say anything to him lol. One thing for just a photo shoot but another on a live fire range.