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

Seems like they have been that way for a while. That factory M4 Carbine lower I have above is 2013 and it's a mixture of pressed/stamped and laser engraved. That M4A1 lower is a few year old also, same thing.

I? am debating if I? should stick with a 10.5 barrel that I? have. Or should I? dish out the extra funds to buy a 10.3 barrel?

10.3 Masterrace.

^ This...

Unless broke as a mofo 10.3 is always the answer

At $110 for BA 10.3" w/ a .070 gas port, you'd have to be real broke. It's not a colt, but it's cheap. I've considered that route for my next build although I'm sure somethin colt will usually be available in the EE.

I just picked up an Andro 10.3 FSB (.070 gas port) after selling my unholy 11.5 upper and fit/finish looks very nice.  Much easier to pull the trigger on that than one of SA's for nearly 3x the price.  Month #11 for NT4 continues .....

Mine does not have the white dot either on the bolt. Bolt looks brand new - I dont see any brass on the bolt face from test firing. Carrier is “c” marked though and bolt is marked MPC. Can’t comment to on the CH as I didn’t get one. Anybody else have any thoughts?

My last shark arms order. No white dot, bolt marked, carrier marked, and CH marked

Attached File

https://www.ar15.com/forums/ar-15/6-5-Grendel-MK18/121-719883/

ill be sticking with 10.5

Holy shit he's still alive. You need your avatar back sir....and a 10.3" barrel.

Im alive, Bro.   Just plugging away at my doctorate.  Christmas got me back into the MK18 game.  Been lurking a little.  Avatar as soon as I find 25 extra dollars haha

Merry Christmas. Try logging out and back in again.

Broooo....I appreciate it big time.  One of these days, Ill pay it forward.

Now every former .mil guy gets to experience that sharp stab in the gut when the round brown enters the room.

Thats all an arfcommer can ask for.
As correct as these are gonna get..
Attached File

Much bettah. Good stuff fridge

Did some shooting with a fellow 18C on Christmas day somewhere along the Pak/Afghan border region.  Burrowed his rifle for some drills before switching over to my G19.

Attached File


CD

This, only got the upper with the BCG. The bolt carrier is "C" marked, and the Bolt is MPC marked as well, but no white dot. Bolt face is clean as well, no brass on the face.

I went with a Rosco Bloodline 10.5? M4 5.56 NATO but only because Garand Thumb told me to.    Though he seems to love the Mk18 platform, his builds are not synonymous with perfect clone builds.
I'll go with a 10.3" on my next build.

Colt M4 lower dropped to $199.99 plus the $10 FFL fee on Brownells. Can be had for around $191 with a filler item to get you over $200 and code H7L.

Colt Lower

While I love GT's videos, IMO he is becoming a marketing/selling THOT.  All he seems to do is push product anymore.   I DO NOT begrudge him for it, however, It is just a simple note to self.  He is also at least pushing quality products.

I was dragging my feet due to the quality issue on these, but that’s too good to pass up!

One is coming my way!  Put $300.95 worth of stuff in my cart and used LQ9 ($30 off $300+).  With AJ it comes out to about $177 before the FFL Processing/transfer fees.  I hope it’s not too beat!  Actually, I don’t really mind about that...I just hope it doesn’t have the magwell issue shown a few posts back.

AJ Invite for $10 cashback if you want it!

Got a visit from CQBR Santa :D!

All decked out with the new Colt Cerro upper and tan M300C:


Colt Cerro Upper:


Took it out to the desert on Christmas Eve for the first time since the upper receiver swap and put 7 PMags through it. Nothing really noteworthy to say about the receiver swap other than the fit between the barrel extension and receiver was much tighter on the DD than the Colt. Otherwise, the Eotech retained zero through the swap; the irons were a little high.

I also refinished the Blade in Alumahyde Magpul FDE and it came out pretty decent (didn't apply on a rainy/humid day this time, heh). Stripped the Aervoe Coyote with Citristrip, gave it a light sanding and degreased, then used a heat gun to warm it before application. Flashed off the two coats with the heat gun and then baked for around 5 hours at 200 degrees. I'm not certain it was fully cured, but it was completely dry and could be handled/assembled after cooling. I took it shooting a few days later and had no problems - the finish is very tough. My first attempt it was still tacky after a few days and never really cured properly. I'm sure it'll last the 6 months until my stamp comes back ;p.

And at $199.99 I'd have very little to complain about on those Colt lowers; pretty damn good deal.

What is your impression of the more upright pistol grip?  I’m considering going to one of those.

If I didn't say your job was a dream job I'd be lying

Not fridge, but I like the more upright grip.  Anything under 14.5 and the more upright style grips just feel more comfortable, less wrist strain.

Someone here was asking about the IUD labels.  Seen square, rectanglar and circular.   Here's a circle one getting replaced with the new rectangle one.
Attached File

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CD

I’m so pumped for my Lower...only problem now is, I should have bought two.

I prefer it MUCH more. I have pretty long arms and it taking some of the cant out of the grip makes it easier for me to keep my arm tucked. I run the bcm grip on all my rifles.
Magpul has the K2 or the K2+ which features a similar grip angle. Not a big magpul fan myself. Only thing I really like of theirs is the ms4 sling.

I think I might give one a try.  Ive got gorilla arms so tucking them in tight to my sides and keeping the rifle pulled in is a strain.

I see the upper receiver tracking I.D. label has gotten less sophisticated since those first ones you showed us.

*scraaaaaaatch*

Just a heads up.

I went through another thread about the Brownells Colt lowers, read all the Brownell's Q&A, and picked up whatever other info about them I could find.

I was fully prepared to get a "CR" lower with a blem'd rollmark.

On the 19th I ordered one, it shipped on the 22nd, and arrived at my FFL yesterday.

I picked it up today and it was a "blem" LE6920 lower.

ETA: I say "Blem" because of the rollmark everything else is just the same as my last 10 LE6920s

Pics of the Brownell's lower

That was nice of you Fridge.

Well that's interesting. I ordered 2 last night, Shipped today already. Will see how that turn's out.

How is everyone else running their M300 on a Gear Sector Mount?  Just got mine in, and set it up like this. Attached File

Damn, just when I was starting to accept the slightly scraggly one I kept wasn't really so bad, you post this :\. I ordered 3 and none were close to that nice, so you got pretty lucky. You should go wager on the ponies or play the lottery or something.

My FDE GS is still backordered. I guess that's what I get for being cheap and refusing to pay $25 more to buy from GS directly, heh.

That's the same spot I ran mine previously, and unless I end up springing for an SR07 remote switch, it'll go back into the same spot; when I actually get the new FDE mount, that is :\. For now I've got it in the same spot using the factory mount.

Gingers don’t have souls, but they have a soft spot in their hearts around the holidays..

Identical to yours just mounted on the other side.

Ugh stupid SF M300C TAN Scoutlights! I ordered one from SF like a week ago and then like 6 days after ordering it I received an email saying opps, sorry it's out of stock but we will have more in like 3 weeks.

I ended up ordering another one from IWC for $220.00 shipped so actually about $2.00 less than directly from SF with that "allthelumens" discount code even. I had my tracking number like 12 hours later, says it will be here in 3 days.

I still have a hold on my AMX card from SF. I called them to find out how long it's going to take for that to drop off, they told me to call back in a week if it hasn't. I called AMX, they said up to 30 days. I'm also seeing where a guy over in the Lights and Lasers section cancelled his order with SF also and they told him "OK" and then a week or two later he got a "your item shipped" notification.

I had planned to buy one of those SF Training SOCOM RC's but now all my Christmas money is tied up in SF Scoutlights and at this point, I might end up with two LOL!

Thanks for letting us know. I'll steer clear of SF then when I order mine. If you end up with 2 it just means you have to build another MK18 upper

Shot the Mod 0 today for the first time.  Felt great to get back into the platform.  Now, because of you people, I have a Colt lower coming.

Yeah, SF seems to have a real problem when it comes to fucking about with your card. They charged me at least 4 different times (maybe 5, I lost count) between when I ordered my M300C and the time it shipped. Each time holding the charge for several days and then releasing it; kinda annoying to have them tying up $200+ every week or so. I get a single hold charge when you place the order to verify funds followed by a release and then a second charge when it actually ships, but they were doing it constantly from late November until it shipped December 18th or whatever day it was. Really odd way to do things.

i dont even wanna BE in here now! *eeeek*

Just got a transfer in from these guys for a customer. Saw the price.. thought I had to share..
https://www.armsunlimited.com/SureFire-Fast-Attach-Rifle-Sound-Suppressor-p/socom556-rc.htm

Dang!

I thought my $825 snag from them for a FDE SOCOM556RC was a good deal...

Yeah annoying as fuck...

I should have known better than to order from SF directly! I called them up one time to get some shims for a 4P which did end up being free but it took 2 months to get them. Unfortunately I didn't know IWC was selling them for $220.00 at the time, that is like $1.86 less than Surefire even with the "allthelumens" code as I mentioned AND they apparently do have them in-stock.

Like I said I ordered a second one from them and received my shipped notification about 12 hours later and I've gotten two USPS updates since then so it's on a truck somewhere and will be here Tuesday! I probably won't even have my refund from Surefire by Tuesday at this rate.

If anyone's looking for a TAN Scout M300C Mini just order it from IWC for $220.00 and use the discount code "Tango" for free shipping.

http://www.impactweaponscomponents.com/product/surefire-m300-mini-scout-500lum-tn/

Got a NT4 Pending but that's really tempting. Shit.

I've had that page bookmarked to keep looking periodically.  I'm hoping that their prices stay low while I continue to save up for it...

What is th e process for buying a suppressor online?  Armsunlimited transfers to your FFL like it would a gun and then you do the forms at your FFL like youre buying from your FFL?