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 guess with NVGs, you don't really use optics for CQB? The Vortex is not NVG compatible.

Fixed it for you @blindrocket.  Does anyone know what sling the Garand Thumb guy is running on his MK18 he didn't mention it.

You can but running NVG's passively really isnt something that the CQBR works well with. That is part of the reason things like the KAC skyscraper mount exist.  Running an active IR laser under nods is easier.

My FSB CQBR is for sale gentleman (chopped M4A1 FSB rail)

A few pages back people were mentioning the lack of Taupe NT4 cans - I personally jumped the gun and bought a black one years ago as soon as I had the funds in my pocket and will add a few notes:

1. New NT4 cans come in Cerakote; clone-correct NT4 cans are Norrell's Moly Resin ('Flat Desert Tan' was the original color name - I'm pretty sure 'Tan Flat (Dark Flat Earth)' is the new name).  Even if you buy a new NT4 in Taupe, it won't be 'correct'.
2. Re-coating the cans is possible (and easier on the older black ones), but to do it correctly, it can be a scary job.
3. The new Cerakote cans have a higher temperature rating and will likely not get the classic burn-off patina seen on the old in-the-wild shots.

Just as a quick side-note, the original cans were NOT KG GunKote - Knight's made a mistake in an older post on here once saying that (they have mentioned elsewhere that it was definitely Norrell's).

The latch and retaining ring are assembled AFTER the can was coated (i.e. they are not coated), and part of the latch installation involves a pair of one-way roll pins that bottom out on a flat surface.  As such, these two pins must be drilled-out to remove the latch.

This isn't quite as bad as buying a Mk 12 can (AEM5) and not getting it knurled but later wanting the knurling (can't be done due to mandrel requirement)... but it's still a pretty iffy job with plenty that can go wrong without a good drill press.  I just left my can black, but I've had a bottle of the Moly Resin sitting in my closet for a few years.

Since Taupe NT4s are still being issued, both the old and new coating would be plenty "clone-correct".

Form 1 trust approvals in june.... cmon october..... I need a reason to start my MK18s already!

No shit? I better get my scar barrel sent out then.

I looked just now and they cashed my check today for the F1 on my Colt M4 lower :D. It arrived 01/11, so not too bad at all. Come on 4-6 months!

Pretty soon the only thing left will be to decide between a B5 SOPMOD or Colt N1. I have an FDE B5 and a brand new black B5 that I'm thinking about rattle canning - I'm leaning toward one of the SOPMODs, but I've had this particular N1 for 20+ years and I'm kinda nostalgic.

OP Lives!!!

Just rattle can yours....

Ah, I didn't realize this - thanks for the heads-up!

And I didn't want to gum up the latch - this is why I didn't rattle can it.

https://m.imgur.com/CHOvav8
https://m.imgur.com/6EuWKm4

Man I love the look of car stocks on the cqbr. The only reason I haven't picked one up is a sopmod full of batteries really helps the balance.

Yeah, balance is one of the main things swaying me toward the SOPMOD - that and the comfy pillow cheek weld. A CAR might not balance as well with a light and suppressor up front or be quite as comfy... but it looks awesome! If you look good that's all that matters, right? :\

I'll reach out to a friend, who is indeed OAF and see if I can post some of his pics that he has on the book of faces.  He was rocking the CAR stock.

Post 'em up if you can, I always like seeing a CQBR with an N1. Although I think a SOPMOD probably has some advantages, none of that is to say they can't be used effectively - I mean, if this gloriously bearded Viking bastard uses an N1, it can't be all bad, lol.

That dude looks freakishly like my friend....he is a soulless ginger after all.

Does anyone have a ballpark total weight difference between a MK8 upper and (now fashionably too heavy) RIS II?  I get 5lbs 10 oz with this set up plus M3X on the other side.

Not too much. The hand guard itself is 3.5 oz lighter but you'd have to add rails to it to be able to mount your accessories. About the only way to get lighter would be to ditch the add ons and go to no optic or a small RDS.

I wonder what they're using that SI Swimsuit mag for?

Oh, I expected some huge difference.

Question about this!

So the current BLOCK II KAC sights are NOT Micro? I've seen a few of those USMC marked sights and all the ones I've seen are 600 Micros.

Put some masking tape on the latch...

What, you thought the spray bottle of CLP was for the weapons?

I have never seen or issued a 600 Micro.

Attached File


KAC P/N 98474
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Attached File


CD

I think this is an issue about where shit comes from (the whole procurement/budget thing).

Typically, at least in pics, it's really common to see MARSOC guns with stuff all from USMC, not SOCOM or whatever.

Usually see them with EXPS3-0 instead of SU-231a, usually with 600 micros instead of 600s/MaTechs/etc…, usually with a PEQ-16 instead of an LA-5, KAC can instead of Surefire, etc…

Just reading into most of the pics I see it's like their whole guns get kitted out with USMC funds, not SOCOM funds (or whatever. Don't worry, Augee will be in here soon to correct all my dumbass terminology that I'm probably getting wrong. Sorry).

I think it's safe to assume all the micros you see on USMC CQBRs are USMC marked micros. If you're cloning a USMC gun, I think a USMC micro would be pretty cool. If you're cloning an Army/Navy gun, I don't think they'd be super "correct" (whatever that means to anyone personally).

OK so what would a correct USMC Mk18 RIS II setup be? What parts would be "kosher", optics, lights, stocks, dildos, mounts, flash hiders, cans etc.

3 quick questions for yall clone nerds heheh

1. In order to create a mk18 clone you have to pick your time period in away? Earlier vs later fielded


2. That being said mk18 ris II is considered 'Old" now correct/ MK8 is the new new?


3. What is the most current set up coming from crane? I know its 10.3, .070-0.71, lp block ,b5, eco-tech or elcan. What handguard, surpressor adapter for most current clone?

Thanks yall. Going be the first SBR in the collection should be fun!

Pick a time period and look at MARSOC pics from then is my best advice. You'll get an idea of what is okay and what isn't and what can go together and what can't.

There is the base weapon which is simply the Mk18 Mod 0 and the Mk18 Mod 1. Or there is a base CQBR URG or 10.3" RIS II URG. The accessories have been changing constantly however which will determine what is correct for any given time. Also, there are SOCOM accessories and branch accessories.

MK8 is not issued. Guys just like to post pics of their rifles that have 10.3" barrels and MK8s. However, USASOC most likely has a 10.3" version of their URG-I that we haven't seen yet which would have a 9.5" MK16.

Most up to date SOCOM Block II parts would be 4 prong, RC, taupe front sight, Matech, non micro 600m rear, WMX200, EXPS3-0 maybe?...

Yours the man!

dd ris II for block II?

Yes. Block II is M4/M4A1 upper receiver, M4/M4A1 BCG, M4/M4A1 non SOCOM barrel with FSB cut down to 10.3" and dimpled, Mk12 gas block, KAC or SureFire 4 prong muzzle device.

Well I don't think you're going to find too many things that are kosher for Army guns that aren't kosher for USMC guns just because they have access to SOCOM stuff like the rest of them. You'll see marsoc cqbrs with LA-5s, Full size 600ms, etc… every once in awhile in pics. About the only thing I haven't really seen is a marsoc cqbr with Surefire flash hider / suppressor. I think rather than kosher, you'd just want to get it "USMC looking" as possible. Things like Waffle M4 stocks seem to show up a ton in photos and "seem" way more rare on Army/Navy/AF guns for instance.

If I were personally doing a USMC build I'd do:

- EOTech EXP3-0 with older L3 logo
- PEQ-16 (best) or PEQ-15 (Still acceptable but not quite as USMC looking)
- WMX-200 Fixed
- KAC NT4 flash hider and NT4 can
- KAC Taupe front sight
- KAC 600m Micro USMC marked rear
- Waffle -> SOPMOD -> CTR (in that order)

Kinda where I'm at now. I've got the USMC marked micro. Waiting on some Form 1's to come back etc.





*Edit* No, the Colt M4A1 lower is not on my Mk18 upper in that photo while I wait on a stamp! Yes someone asked...



COLT LE* Lower


Brownells CO_T CR* Lower rocking a G SSA-E!










MK8 Upper, just cuz!

I need to get that ambi and that pressure switch! :)

Also can you explain the black rubber band looking thing on your N1? I keep seeing people rocking those. I assume its to hold light sticks but what is the black rubber band? Looks heavier duty than an office supply store rubber band.

https://www.ar15.com/forums/ar-15/rubber_band_on_collapsible_stock___why_/118-418828/

Here's one source, although there may be other options...

https://www.bravocompanyusa.com/GEARWARD-Ranger-Bands-20-Pack-VBOST-Appplication-p/gw-ranger-band.htm

Chems/IR chems for buzzsaw etc.

Who wants to guess what I built today in the Mk18 world?

CD

Ummmmm let me guess, an Mk18 right?!

Aimpoint T2 with Larue mount or Eotech 553 FDE.  Can get both for same price.  Which one should I go with for my Mod 1 clone?

10.3" with new shorter mk16 geissele rail.

Do tell...

Those will be coming, not today however.  Pictures in an hour or so.

CD

You can also cut up a bicycle inner tube.

Best source for the ambi right now is Arms Unlimited, though I think they're out of stock right now. Pressure switch is an SR05, I like it because there's less slack than an SR07. The stock has a Ranger Band, BCM sells them. People use the bands for chem lights and to tie up slings when being stored, also eliminates any wobble on the stock latch.

Difference between Crane's cut down 10.3" Govt profile and FN's new 10.3" SOCOM bbls.  Gas port is a measured .070"
Attached File

Attached File


The parts: FN bbl, upper, BC and bolt, DD RIS II Mk18, PRI CH, SF4P FH and KAC front sight.  Rest of parts are all govt contracted.  Only thing that's used was the Forward Assist, almost selected a teardrop M16.
Attached File


Assembled and installed on lower w/SSF trigger.  Second we built this week with FN bbl.  Bit heavier up front of course.
Attached File


CD

COME ON WITH THE PICS

Eotech 553

CD

Nice