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

Keep checking EE for KAC or P&S handguards.  Should be around $150.  Here's a Surefire M73 rail.  I had this on my M4A1 in Iraq in 04-05'.

https://www.ar15.com/forums/Equipment-Exchange/Surefire-M73/159-2029833/

CD

Repost from last year.  Mod 0 has a KAC RAS (built one upper with RIS too)

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CD

What optic is that on the top upper

3x off this guy.



CD

Wish I could buy a nice shiny new SF4P like that

New barrel and 4P put on in Jul after shooting out the old barrel.  This new one is at around 2500 rds already.

CD

Just perfect.

Shark arms has some P&S for $140

Went to post this in another thread and realized Butthead is rocking a Mk18

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CD

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CD

@Combat_Diver
When guys have their two uppers setup like that, which one are they using more frequently? Like 60% urgi/40% mk18 etc?

Mission dependent really.  When I inspect only means upper is what they used last or projected to be used next.  Seems lately more URGI being used but there's always one or two running the shorty.  Also they may be running a Mk17, M2010, etc for their long gun and keep the shorty on.

CD

You think guys are going to replace using the shortys in general in favor of urgi?  I know mission dictates gear but I think last time I weighed my cqbr and urgi set up the same they were very close in weight.  Is the 4 inches of length enough for entry designation?

Depends and don't forget when you add the suppressor.  Come a long way since I just had a XM16E1 and M1911A1 on the team and only two sets of PVS-5s for the whole detachment.

CD

Oh no doubt things have changed a lot over the years.  I’m just curious why guys in general are choosing the urgi over the cqbr.  More versatile?  For instance I think I asked you years ago back before urgi was a thing what the trend was in what guys were running and it was mostly cqbr with a couple of m4 block 2s.  Now it seems to be swaying the other way and was curious if it was weight specific or something else lol.  My socom can is still awaiting approval so I can’t really compare much on how much the suppressor added makes a difference in use and maneuverability.

Every team is different and mission dependent.  There is also the newness factor with the URGI.  Right now the one team that your seeing pics of now is just what they determine to be the tool for them.  

CD

They’re operating more heavily in an area with typically longer engagements and proportionately less door kicking.  I’d say that’s a major factor no?

Stuka himself said that’s why he went back to the longer set up.

Isn't the URGI essentially an M4 with a Geissele rail?

Geissele Mk16 free floating rail, low profile gas block, DD 14.5" mid length gas, Geissele Airborne charging handle and Surefire 4P FH.

Lower and upper receiver are the same. Everything forward the receiver is different.  Only length would be similar between the two.

CD

What scope mount is that on the scope for the red dot?  Is there something that would work well with just say a Holosun reddot ontop of the scope like that?

Looks like a mount similar to the Reptilia RMR mount and the Holosun 407, 507, and 508 use RMR footprints so it would work just fine.

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Yes I would agree and read stukas articles.  But you’re even seeing a lot of urgi’s with eotechs which would negate the need for 14.5 and longer range engagements.  It would make total sense if they were just running 14.5 and lpvos or elcans but you’re seeing a bunch running eotechs which is why I was wondering why would they prefer the longer setup vs a cqbr especially with the socom attached.

Only have talked this with a couple of guys but there are possibly some who separate those two things in their mind. They want the ballistic advantage of more barrel, particularly with Mk.262, but are experienced enough & competent enough to do adequate or better work with an Eotech. Just conjecture, very small sample size.

Maybe pulling this one out of my ass, but I remember hearing some units would use one upper during the work up and save the other one for the deployment (the one that better fit their mission profile).

Q, what scope mounts would be a rec for an in-line Aimpoint clone, not the small RMR's but the actual aimpoint t1 clone.

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There I go again being sacrilegious.

Sacrilegious or not that thing is hot

Not saying it wasn’t the case but it shouldn’t have to be. It’s not hard to run companies through the smalls arms repair guys.

Just something I remember hearing while back. Definitely not gospel. I'd like to hope socom has better repair logistics then what I witnessed then the conventional side and I'm sure they do.


On another note, skyscraper mount should be here sometime this week so I'll be straying even further away from the clone gods. (Though it's all been seen ITW)

Not hard at all. BTDT.

Just makes for some long days is all.

We ran through entire aviation units guns in a matter of days. Everything from M9's to the door gunner 240's and everything in between.

First visits (we went to them)were spent doing annuals(inspections and gauging) and making parts order lists over a few days, next visit was after parts arrived and everything was made FMC.

Infantry units generally brought their stuff to us, but similar concept.

The "fly away" missions to unsupported FOBS were my favorite. I love flying (especially in helos) and enjoyed the camaraderie of the more austere environments moreso than the fishbowls of large bases like BAF.

Good times. Spent plenty of time shooting the shit with the joes at the smoke shack. My time with the germans and mongolians at mazar is something i'll never forget.

I miss those days.

SOCOM does have 91F with each BN and a civilian contractor who works specifically on SOCOM weapons.  Positions are CONUS and OCONUS.

As APSArmament stated, great flying around to visit ODA's and talking to them.  Plus you get to play with the captured stuff.

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CD

I'll look next time to see what mounts they are using.  I'm running a DD mount on mine but its not QD.

CD

Aww, shit son... fresh 5500ct box of Hornady 62gr FMJ up in dis muhfucka :D.

CQBRs say, "Gnom gnom gnom!"


I wasn't really running low, but having another 5500 round buffer between me and desolation just feels better, lol. Plus, I kinda wanted to hang onto my Hornady 55gr SPs. Compared to other bulk 55gr/62gr options, they're probably the most effective as a defense round in a pinch--at closer ranges, they're pretty nasty.

Would've preferred to get more 55gr to avoid having to work up new loads, but it's getting so close to the election I figured I better get while the gettin's good :\.

I'm also a bit curious to see how the 62gr FMJs do accuracy-wise. I've gotten excellent accuracy from the Hornady 55gr SPs (.43" 5rd groups at 50y), so it should be interesting to see how the 62s compare.





The only complaint I have is these damn panic prices... costing me 14 cents per round ;p.

....And here I am struggling to maintain a full combat load worths if ammo and dreading having to rezero my rifles.

Ouch... yeah that's rough :\.

I'd definitely be in a lot worse shape if I hadn't finally bit the bullet on reloading after putting it off for years. The timing was just right to start stacking deep before things went into full crazy-mode.

If you put in the effort you can still get it for 35-40 cents a round.
It takes effort.

Depending how far from Texas boarder you are I may be able to help at non retarded prices

I love the juxtaposition of everyone's perfectly posed and photographed and post-processed clones next to C_D's pictures where he's just like "here's a gun on the floor, you know you love it"

When you only have a short time to inspect them, here's another.

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CD

Finally “finished” this thing. I think i like it!

Your photos are the epitome of "from field to table."  
BAF background still not as intriguing as your last outlying "shop" though.

Looks like the party number not the nsn

Range day is the best day! (Wife P.R. On the left) she had a blast with it this morning... guess iam going to have to SBR it now.... also the highlander isn’t mine, it’s a loaner until my truck comes in that I ordered so don’t judge me

*is it wrong that I love shooting my MK17 more than my CQBR?