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).

----------

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.

----------

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

----------

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

----------

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).

----------

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)

----------

Link to previous threads

 Previous Mk 18 / CQBR Thread Part I
 Previous Mk 18 / CQBR Thread Part II

For you guys that had a 80% lower engraved. Are there more than 2 different engraving schemes available for this series of clones? I sent an email out and in the reply I was shown a mock up of an M-16A1, then of course I saw the M4A1 here in this thread, but now I'm wondering if he does any more?

I'm really new to the clones, I didn't know anything about them until recently, don't know why....lol. It all started when I took my Nat'l Match A2 out a few months ago, fell in love with it again, then decided it needed an upgrade but in the middle of it just ended up building out an M16A4 to keep him company. We didn't even have them when I was in the Corps..

Put together my Mod 0ish upper today. LMT 10.5", LMT rear sight, KAC RAS, Aimpoint ML3 in LaRue mount, B5 SOPMOD. It's temporarily on a lower that I normally use for my 300 BLK upper until the Form 1 is approved for it's very own lower.



I need to decide what can to use. I have a few choices, I think I have already decided but I'm curious to hear what you guys think. My options are:



-KAC QDC (aka Corncob Mk2) already in my possession, currently lives full time on a KAC 11.5" Mod 2.

-Surefire RC2 already in my possession, currently lives full time on a KAC 16" Mod 1.

-Sandman S should be approved any day now

-Specwar K won't be approved for a while, but I have a Specwar 7.62 I can use in the meantime with the same mount.



Of course if any of you guys know of an NT4 in stock in Texas there is that option, too...

Have never been big on a magnifier but came across this anodized one and grabbed it.  I'm liking it, but man this thing is really getting to be a pig.  Definitely not something that will always be on the rifle.

Purchased a PEQ-2A today. Uh oh Mod 0 is entering it's final stages.

 

Looks good, gotta ditch that LT mount though lol... Big Larue user here too, it was hard to switch over to clone correct mounts (and triggers, have several MBT equipped...  but the Wilcox is a decent mount I've found.  KAC makes one as well and is the nice Alum one that the Wilcox is patterned after, I think?


Bought a socom-rc for mine, partly b/c i will be able to use it one some other rifles, partly b/c I couldn't find an NT4 - but if I run across an NT4 I may pick one up as well.  If it were me with your current inventory I would just run the QDC or RC2 for now and pick up an NT4 when you can find one.

Hell yea! PEQ 2 mod 0 maffioso





 

How inaccurate would it be if I were to build a MK18 Mod 0 out of an A2 lower instead of an A1, and then stuck an A1 grip on it...

I only ask because NDS is out of stock on A1 lowers (And will be until after 41F takes effect) and I want to get an SBR  without having to submit to the 41F nonsense.

Not incorrect at all. Plenty of Block 1 CQBRs on M4A1 lowers, even still today. Grip is just preference. A2 would "look" more correct but A1 is just fine.

looks heavy

When you say you are wondering if "he" does any more, was it Braceman that showed you the M16A1 example?  If so, he can do almost, if not all, engraving variations that you might want.  Mk18's were originally built on M16A1 lowers.  CQBR's are/were built on both M4 and M4A1 lowers, and they are marked differently with 2 different mfg rollmarks.

Doesn't feel heavy. The Elcan actually balances out purdy well.

What did you use to cut it?

For those with both a Mk18 mod 0 and mod 1, which do you enjoy shooting the most?

Mod 0.  Feels lighter even though they weigh about the same.

A beer, a brand spanking new hacksaw blade, one Dremel cutting disc, and a bastard mill to "smooth" her out after I was all done.  I almost had a lapse of judgement and nearly chopped off the 2 front screw holes to mount the lower rail to the upper.  

ETA: I almost forgot that I used a dremel "sanding" bit to smooth out the lower rail section to "melt" cuts a hair as they don't quite line up perfectly when cut.

Mod 0.

You can't go wrong with either one. I like the mod 1 better because of the extra rail space that allows me to grip the rifle further out and position the light/laser switches in the best spot for me.

I went with Mod 0 because of Insurgency. Anyone here play?

I would drop all the other slots so I could fully equip the MK18, the thing is a beast in game.

Haven't posted in a while. Finally got to get her out and play today.

Collecting parts for a mod 1 right now.. Snagged a mk18 rail for $350 on the EE last week. Anyone have the link for the clones page on fb?

Forgive my lack of clone etiquette but I'm around page 550 in the thread and saw an issued rifle with a Larue mount. I'm an LT fanboy so mine is staying. With a weird stroke of luck I found a rail today for a steal. Planning on getting the correct sling plate even though I saw a post in the thread with a bunch of pictures of the ASAP plate being used.

After having and shooting tons of sbr configs, to include a mod 0 and mod 1.... The mod 0 has been my favorite. Just shoots like a dream

Yep, I emailed Braceman. And I've been looking at roll marks and specs all evening. Thanks for the info on the lowers! I've actually compiled an excel spreadsheet to help me learn what's what. And I'm pretty close to figuring out what I'm getting engraved. Not sure how far I'll take this yet though. To be honest I've seen a lot of variations in usgi Mk18's.  Enough so to think that there is no defacto list other then certain items like the rail, barrel, sights that certain Mk18's may have.  It's pretty interesting!

You know PSA buffers are Chinese right?

Source?

Put a couple thousand rounds through them and tell me they are American with a straight face..

I'd say build the rifle you want unless you're trying to impress the clone whores in this thread. If you want to be clone correct then have at it. The Larue mount along wit the ASAP plate have been seen in the wild but the ninnies will tell you you're wrong.

Just be sure that you don't confuse CQBR block I and ii with mk18.

Just one "problem" with that:  this is a clone thread...you know, for people who are trying to build accurate clones of their or other's issue weapons.

So if you're not interested in building at least a fairly accurate clone, this thread's not for you.

It's all I had laying around. It was on there just so I could function check it with the upper. The old buffer tube that I had was a commercial tube too

I've got a couple with PSA buffers and have never had an issue.

lol buffer shaming is a thing now?

I've toyed with the idea of changing my mod 0 to a mod 1 for the extra rail space but I've decided not to do it. I just enjoy the mod 0 too much.

20160617_210907-01 by T B, on Flickr

Really....

We know this is a clone thread but nitpicking just one part out of a great photo is a little too much. He went out of his way to engrave that lower, it looks fantastic.  The focus was the lower and the rest of us are glad to see it. What is irrelevant to the thread are comments about stuff that are not the focus of the photo. Comments should be constructive and positive,  why rub someone the wrong way for no reason? We're all here to encourage each other aren't we?  We don't know why he had the buffer in there or if he was taking it out and it shouldn't make a difference.

Well.........we've covered (and argued) about every other thing regarding the Mk18/CQBR, so why not that?

No no......it's ok.........I'll see myself out the door til I can acquire a buffer that I can trace it's legacy directly to Colt with a certificate of authenticity.




Sarcasm BTW..........fuck that other guy.

Man, I am running JP silent capture springs in my clones.....

You better leave too

Forgive my ignorance...is there a difference between a Mk18 Mod 1 and an M4A1 CQBR Mod 1? (I know, I know...stupid question, right?!)

I've read the specs in post 1, but I keep seeing people saying they'd choose the Mod 0 vs Mod 1, because there is more rail space.  I'm confused though, because I thought the RIS (Mk18 mod 0) and RAS (M4A1 CQBR Block 1) were the same length rail???  I figured they were talking about the Mk18 vs the CQBR Block 1 and were just using "Mod 1" for "Block 1", but now I'm thinking there is a Mod 0 and Mod 1 Mk18 that are different from the CQBRs.  If so, can someone post the specs of the Mk18 Mod 1, or point me in the direction of the specs?

Thanks!

TinyCrumb posted all of the specs on page one.

Okay, so then the M4A1 CQBR Block 1 is synonymous with Mk18 Mod 1?

If that is the case, why have I seen people say they like having more rail space on the Mk18 Mod 1 vs the Mod 1?  Is that just because there is less "stuff" on the rail of a Mod 0 or am I missing something here?!

Oh, and Happy Father's Day to all the Arfcom Dads!

The CQBR Block 1 and the MK18 Mod 0 are similar. The MK18 Mod 1 has the Daniel Defense rail and a free float barrel. You're very confused

Just imagine that my M4 was 10.3" with the same rail and you'd have a "Mod 0". The CQBR (which some refer to as a "Mod 1") has a longer rail system. It's a good 2" longer than the KAC RAS.

MK18 - Full issued gun. Looks simialr to the CQBR Block I

CQBR Block 1 - It's a URG for the M4 and looks like a MK18

CQBR Block II - It's what airsofters call a MK18 Mod 1.

This is pretty cut and dry.

I've been seeing mod1 so much on the past few pages and wanted to say something.....

What were the ones that were marked mod1 though? They weren't blockii's were they? I vaguely seeing a couple marked us navy mk18 mod1?

Feelings hurt...