what’s the right designation ?
block II CQBR or MK18 mod1 ?
who can tel me ?
Personal preference??
While a lot of people use the designation MK18 Mod 1, it’s not an official designation.
The “Mod 1s” are issued as uppers only to be placed on an issue M4.
Even what most people call MK18 Mod 0’s are CQBRs.
Thats what i understand to , as far as i know
I have already read that the “MK18mod1 designation” is a common misunderstanding due to the "Daniel Defense MK18 ris II rail "designation.
Is there some more “closing” information to find about the MK18-CQBR “correct” nomenclature ?
There’s a pretty huge dedicated thread on TOS that has some good info. I’m the OP of the current iteration and I tried to describe it there.
But essentially there’s no such thing as a “Mk 18 Mod 1”.
The “Mk 18 Mod 0” was a complete weapon system issued in the Navy that came in either a 10.3" or 14.5" configuration.
The CQBR is just a 10.3" upper receiver meant to go atop a M4A1 lower (or in some cases, old M16s). Most of the “Mk 18s” you see aren’t Mk 18s but just CQBRs from the original SOPMOD era. The current ones are just upgraded to be more in line with current SOPMOD accessories (Block II), so the DD rail, ATPIAL (LA-5), WMX-200, etc…
So, if you’re looking for the uber nerdy technical correct term, it’d be something like “M4A1 with CQBR and SOPMOD Block II accessories”.
But, if you’re looking for what everyone knows them by, including those who carry them for a living, it’s usually just “Mk 18”.
Concur with the above. The Mk18 is a Navy nomenclure and Army SOF its the RIS II URG. Its my retirement job now building them down range.
CD
Thanks for the info so far, guys !
So TC your the guy from “THE” mk18 thread 
i find its realy awesome, the most complete and informative guide so far, on the web, my compliments!
About the whole SOPMOD-CQBR-MK18-story there’s plenty of information to find, just to a certain time, and ammount !
(for example there the CRANE presentations of the SOPMOD)
but the most recent developments are not documentated “officialy”, anymore ?
Same for the MK18 blockII CQBR question, or the most recent SOPMOD contents .
Thanks. I’m no expert though, really I’m just an internet nerd with far too much time on my hands and a peculiar interest in these rifles.
I don’t think you’ll really find much documentation around a “Block II CQBR” because that’s really two separate things. The “CQBR” is just one receiver, it’s the same as it always has been. It’s the “accessories” on it that have changed, including the rail system. And there’s plenty of documentation out there on the latest “Block II” accessories of SOPMOD. An example:
But anyway, for the best information, Combat_Diver is really your man. The guy builds the real deal of these for work, and he’s been incredibly generous with his time helping us with information and pictures. He could give you far more accurate information than I could.
Pretty sure Mk18s actually have the whole CRANE info laser etched on the right side of the mag well. CQBR is a URG put on a M4A1 lower.
I agree with al those statements, seems very re reasonable to me !
But why named Daniel Defense the RIS II rail as the MK18 rail ?
Same for the KAC front flip up sight ?
I think these manufacturers-designations are causing the confusions !
There are several different versions of the Ris II rails from DD calling it a mk18 designates its intended use on sbrs
I mean this 9.5" version in there description there declaring its developed for the MK18 ?
Can’t comment on the deveolpment but several different DD RIS II are fielded for both 10.3" and 14.5" bbls. They may use either a low profile gas block or FSB depending on issue. Did see my first 14.5" FSB DD rail in the field yesterday (had some NIW in Astan to issue and field but demand was for the 10.3" low profile ones) Have some of the 10.3" and 14.5" low profile DD rails in Kuwait for rebuilds.
CD
CD
Here’s mine…I can give the specs if you want, as best I know them at least.
*edit…just realized this thread was forever old
Did the original MK18’s have a 10.5" barrel instead of the current 10.3" configuration?
As far as i know the MK18mod0 can have either a 14.5" Government profile barrel , or a 10.3" CQBR barrel
Navy guns with RIS IIs are called Mk18 Mod 1s AFAIK. last I saw, there was a Mk18 Mod 1 with 10.3" barrel and DD Mk18 RIS II and a Mk18 Mod 1 with 14.5" barrel and DD M4A1 RIS II.
A MK18 has a 10.3" barrel. A M4 has a 14.5" barrel. Some MK18 Mod 0’s had 10.5" LMT barrels but most were 10.3" Colt barrels cut down from Colt 14.5" barrels.
What buffer weights are ya’all running in these?