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

Dude...AZ

So...would I be killed for doing an EXPS 2-0 and having it cerakoted tan???

Big block II mail day today
Attached File

Wrong stock, Hoss

Thanks for the info. Last SBR I did the cleo sat with my paperwork for a month. Im glad they changed that.
Thats fast!

Or just take the money you’ll spend on cerakote and get the EXPS3

See I almost posted that same thing minus the BOING eyes. But then I figured he prob already has a EXPS-2, and thats why he asked.....

To answer your question smitty, the main diff will be no hood cut out for NV button. And no logos /markings left after cerakote

Yeah I know. LMT Gen juans are too bloody expensive! Hard to justify the price tag when the b5 was half the price. And I need my QD mount.

Lol. I hear yea man. This stuff is too expensive!

Submitted paperwork today on two of these. The long wait begins.

$25 for cerakote through a buddy...

Ah yes, wasn’t thinking about that! . Might just have to spring for the 3-0.

Yeah good deals can be found, let alone people selling them at reduced prices on the EE. When building mine, I just sprung for the exps3-0 for color and capability correctness....despite not having NV...it gives me options in the future!

Two select fire guns

Attached File


CD

The OG Steyr AUG!!! With that silly "scope"

What the optic/sight on the AR? Looks tiny, T1 - T2?

And thanks for the UID info!

Show-off! You get to shoot some of the coolest guns. And select fire too.

ETA- well I’ve got 2 form1’s filled out. One form 1 suppressor, and an sbr for my colt lower. Just gotta send in the finger print cards and wait the hopefully short (relatively) wait and I’ll be in business. The suppressor won’t be clone correct, but it’ll be 100% user serviceable and it’ll get the job done.

Well that makes me feel all warm and tingly inside.  Now, are Magpul D-60 drums clone-correct?  

Finally took the CQBR V2 out for a test fire and to get it zeroed. Meant to take it last time, but I realized I hadn't cleaned the bore/chamber at the last minute and left it behind :(.

Function was 100% shooting Federal M193 and Wolf WPA 55gr unsuppressed with an H3 buffer. Still need to get a front sight :\.

Attached File

I feel like this was skimmed over but anyone else receive their stripped Colt 10.3 from G&R? I feel like they were using the roll mark "C" in the pictures and description as bait to get people to buy in...my barrel/bag had the following marks...

On the barrel...

13629 M P
5.56 NATO 1/7

On the sealed bag...

SP64046
BBL & BBL EXT. ASSY
QTY = 1
S/O # 81161

Not sure I understand. All current Colt barrels are marked 13629 as are the new receivers. C was the prior marking for both.

Same stuff.

Attached File

Can I borrow a case or 5?

That's an air lift I can use right about now

You had your opportunity to buy mags, don't be greedy.

I think it's more a case of them failing to update the product page. The previous batch of factory Colt 10.3s were all C marked as far as I know. Mine is dated 01/19 and is marked C MP.

Either way, since it's hidden it's not quite the same as buying something like an upper that is supposed to be C marked and getting a CAGE code upper. I wouldn't worry about it... everything going forward is going to be CAGE marked.

Hard to say if they went from C to CAGE to C again or what, but I wouldn't worry about it. Still the same parts

......but mags are not BOOLITS!

T1

CD

Here might be an interesting development. This image was posted to CRA by a contract armorer. The cut down and dimpled barrels are supposedly from Crane. Is it possible they've depleted their supply of govt profile barrels and are now chopping SOCOM's instead?

They're definitely being used, but I'm not sure if the current supply is all SOCOM profile or a mixture of the two. @Combat_Diver would be the one to ask.

The 10.3" SOCOM's that CD received through his supply were manufactured by FN. Those are factory dimpled and not drilled for FSB pins. Conversely, the barrels in the above photo are Colts—They're visibly threaded and dimpled post park, typical of a barrel modified by Crane. To my knowledge and recollection, this is the first time seeing that done to M4A1 profile barrels.

Crane has been sending me FN SOCOM profile 10.3".  We just got a shipment of 10.3"s at BAF but haven't seen them yet.  I'll be there next weekend to look at them to see what Crane sent.  Possible they did cut Colt SOCOMs down.  Does look like Cranes work.

CD

@cjwwd2 - I hope you took advantage of the rebate!

Of course!

Not a bad price on a 11.5” socom(fbi) colt

https://www.armsunlimited.com/Colt-M4-Commando-11-5-inch-556mm-Barrel-Assembly-p/sp402251.htm

Wrong barrel length for this thread

Not if you cut it down to 10.3”

Although technically these look like FBI profile barrels(no cuts). If you scroll up on this page you will see discussion on the use of cutdown Colt Socom barrels on the MK18. It has been covered on here before as well.

I personally have a Cut down colt fbi hrt barrel on my mk18 0. It use to wear a govt FN 10.3, but I swapped to the colt and never looked back. The pros of the 10.3” socoms far out weigh the one con when compared to the gov profile IMHO.

Double CQD mounts are just exquisite



And then a tan ADM Surefire marked scout mount off a new production M952V on a M600DF.



Prime

Don't recall any of my other 4p's changing colors but noticed mine did after the range yesterday lol.

Attached File

My favorite ever

What do people think about this barrel, price and supplier:
https://charliescustomclones.com/colt-10-3-mk18-factory-barrel-govt-profile-fsb-c-marked-barrel/

Barrel- great
Price- horrendous
Supplier- expensive

Are you shooting FA?  I though there weren’t massive pros to the Socom over the Govt profile unless you were going FA...

That's just the 4 prong showing it's true unicorn colors

What was firing schedule on that? I don't think I have ever seen that either. I would guess that is the copper buildup on it that is starting to color? I don't see how you could burn through the coating and get it hot enough to heat color the base metal.

This is the brand new replacement 4 prong after I just replaced my other barrel that was shot out.

It has 2,100 rounds on it so far.  No full auto on this one yet, just standard firing schedule.  If it wasn't heat treated correctly, it should be now lol.