Lately, I have been giving some serious thought to doing a Mk12 build. I'm not really interested in being 100% "clone correct", so I guess my build will be more of a Mock 12 than a Mark 12. I have a Colt 6920 that doesn't see much use in its current configuration, so I'll probably use the lower, upper receiver, and BCG from that gun. As far as everything else goes, I'm open to suggestions. I like Knight's Armament stuff quite a lot, so I'm leaning towards their 2 stage trigger, RAS handguards, backup iron sights, and bipod adapter.

I'll probably go with a Harris Bipod and a Leupold 3x or 3.5x optic. I know the PRI gas buster charging handle was used for the most part, but I'll most likely go with a Radian Raptor ambi charging handle.

As far as barrels and muzzle devices go, I'm not really sure. To be close to correct, I would need a Douglas barrel with Allen Engineering brake and collar and an AEM5 suppressor. But I sort of want to use one of the cans I already have, so I will probably deviate from clone correctness here.

So if you've done a Mk12 build, whether it be Mod 0, Mod 1, or Mod H, I would be interested in seeing/hearing about what you did and how difficult the parts were to find.

Thanks!!

Mine is roughly based off of a MK12 Mod H, but like you I didn't necessarily want to use the specific brake and collar and all of that because I wanted to be able to run my own Form 1 can on it. I also wanted more variety in my optic, but wanted to stick with some things like the ARMS rings and the "right" look to the optic based no that. I've been building this thing slowly over the years (since about 2013) and most recently added a full length bottom rail, AFG, and a DeltaPoint Pro in an offset mount that aren't even in this photo (the mount is, but not the actual MRO).

Since I've been building and swapping parts on this continually since 2013, I can't really say much about availability. I've grabbed things that I wanted when I saw them...sometimes at great deals and other times paying full price because I wanted what I wanted and I wasn't going to wait around.

Not sure if this image will come through or not...it's hosted on another forum and I don't know if that will allow it to be visible here or not.



As for build list itself, I'd have to sit and think about that...
Aero Precision lower
Geissele High Speed Match trigger
Magpul PRS Gen 2 stock
JP Silent Spring
BCM Gunfighter Grip Mod 3
Troy ambidextrous Mag release
Odin extended mag release (primary side)
Radian 45* safety selector

Aero upper
Rainier Arms SPR 18" Mid-length barrel (don't think they offer this anymore - it was a white oak blank) 223 Wylde chamber, 1:8 twist
Dead Air KeyMount muzzle brake
PRI Gen 3 handguard
PRI rail-mount front sight
ARMS 40L rear sight
PRI "RECCE Rail" bridge
Gemtech suppressor bolt carrier
AXTS Raptor Freedom Bone charging handle (now known as the Radian Raptor SD)
8" PRI bottom rail for the Gen3 handguard
Magpul AFG rail mount
ARMS 22M rings, with tactical ring cap and rail section
Sig Tango4 3-12x42 scope in black with MRAD Milling Reticle
Leupold DeltaPoint Pro in offset 45* mount out at end of handguard
Atlas bipod with ADM quick-detach mount

The thing shoots like a laser beam out to 500 yards (as far as I've shot it) when prone or from a bench. But she isn't lightweight by any stretch of the imagination!

I've been trying to decide between building a Mk12 Mod 0 or just a nice accurate AR, for target shooting and some limited FT/R competition (out to about 600 yards) and maybe popping small critters out to whatever distance I can reach. Either way, IF I get around to putting a can on it, like you I'll probably go with a newer design than the AEM5, so it won't be a true Mod 0 clone. Still undecided. I can re-purpose/rebuild an existing rifle into the 'nice accurate AR' for a lot less $$ than the Mk12, but the Mk12 is just so damn cool that I'm starting to lean that way. I don't like quad rails, so it'll definitely not be a Mod 1.

The only thing Mk12ish about this is the 18in barrel.

quote:

Originally posted by WARPIG602:
The only thing Mk12ish about this is the 18in barrel.

And if I decide to go with the 'nice accurate AR' build, that's a lot like what I'm envisioning, right down to the A1 stock. I might opt for a 20" barrel over 18, though. Nice rifle you have there. What optics are you using, and how do you like them?

That first pic looks like a Leupold VX-6HD 3-18. Great scope - I run one on my hunting rifle.

You say "IF" you get around to putting a can on it...I'm the opposite. I have a hard time shooting something that I can't put a can on any more! One of these days I'm going to get my hunting rifles cut and threaded.

quote:

Originally posted by RainMan_PNW:
You say "IF" you get around to putting a can on it...I'm the opposite. I have a hard time shooting something that I can't put a can on any more! One of these days I'm going to get my hunting rifles cut and threaded.

Yeah, it would be nice to have one, but the reality is that most of my shooting is on a range in proximity to other shooters, so a can doesn't really benefit me much. And there are the hoops to jump through - not to mention the wait - just to get one. I'm having a lot of trouble convincing myself that it's worth it.

quote:

Originally posted by Expert308:

quote:

Originally posted by WARPIG602:
The only thing Mk12ish about this is the 18in barrel.

And if I decide to go with the 'nice accurate AR' build, that's a lot like what I'm envisioning, right down to the A1 stock. I might opt for a 20" barrel over 18, though. Nice rifle you have there. What optics are you using, and how do you like them?

Ive used bothe VX5HD 3-15x56 and Nightforce ATACR 5-25x56, both are my top pics in their respected price brackets. A close contender is the Nightforce SHV line.

Like you I initially wanted a MK12, just wasnt cost effective to go clone correct and if not going clone correct, whats the point.

quote:

Originally posted by WARPIG602:
Like you I initially wanted a MK12, just wasnt cost effective to go clone correct and if not going clone correct, whats the point.

Bingo -- function over form.

If one wants an accurate (or whatever) AR-15, it should be built with the end purpose in mind. A sorta-kinda-ish clone isn't a clone. One or two period-correct parts doesn't make sense if modern parts offer greater function, more compatibility with other components, or better accuracy.

I also had a Colt lower laying around and was thinking about a MK12. Instead I ordered the Larue Ultimate Upper Kit with an 18" barrel. Changed the flash hider and put on a Magpul UBR stock. Used the Larue trigger that came in the kit. What a friggen tack driver. I have 4 AR's and nothing else I have (including other style rifles) comes close.

This is the time to take on a project like this.

I cheated and bought a BCM FDE MK12 upper.

I have two MK12 I have been working on. MOD H and a Mod 0. I had a MOD 2 but wound up selling it off to finish up other project.

I’d post but I bailed on photobucket.
Who is our fave photo host now?
I’ll get them up.

Built a Mark 12 …. sort of. Wes Grant at MSTN built this weapon.

Noveske Match upper/lower (found in safe, forgot I had)
Noveske 3 groove 18" 1:8 twist barrel
MSTN / Youngs Machining Bolt.
SLR Low Profile Adjustable Gas Block
BCM Magnesium 16" forend, Key Mod
AR Gold Flat Face trigger
MSTN Taran Butler Muzzle Brake
Titanium barrel nut (cutting weight)
Scope: NF ATACR 4-16 X 50, Mil C
Atlas Bipod.

With 75gr Hornady ELD-M, it is a hammer out to 800 yards.

Andrew

If your gonna clone, clone away. As a Moderator who was speaking about accurate M14 builds put it,”The hunt is the fun part.”

All The rifles shown here are no where near clone level of your splitting hairs.
But it’s fun and it’s a process.

This message has been edited. Last edited by: bigmule,

I think Warpig and Fritz nailed it. If I'm going to build a clone then I'll make it correct, but I'm going to push the Mk12 down into the "maybe someday" category and just build an accurate shooter for now. Some of the parts I already have (I'm repurposing parts of an existing rifle). Basically it'll be this:

Bushmaster A2 lower
Geissele match trigger
A1 or A2 buttstock, tube & buffer
Ergo grip

Generic no-name upper I already have, or I might pick up a match grade upper
BCM Gunfighter or Raptor charging handle
Ni-B bolt carrier
Krieger 20" SS Varmint barrel, 1:7, match chamber, rifle length gas, threaded for a can (from Compass Lake, they'll also supply a bolt matched to the chamber)
Superlative Arms adjustable .875 low profile gas block
Atlas bipod

Not sure about the handguard yet. I prefer a slimmer M-LOK forend over a quad rail. I have one on my carbine made by an Oregon outfit called Stubborn Mule (used to make parts for Noveske) that I really like, but I'm not sure if they make one big enough to fit over this larger-than-normal gas block.

Still deciding on glass, but it'll probably be either a Leupold MK5-HD or a Nightforce NXS or ATACR, something like 5-25x50, second focal plane with a fairly simple MOA reticle.

This isn't going to be a rifle that I'll ever use iron sights with, so no BUIS and no need for a QD scope mount (except maybe for transport).

Trying a new pic host.
Here’s a, getting ever closer, MK12 Mod H.
I’m gonna skip the noveske barrel... it’s plenty accurate.

I think too many people get caught up into what one particular branch uses for weapons. In these days of AR-15 component options out the wazoo, it doesn't make much sense to spec out a rifle or upper to what essentially was the low-bid cost for a given government spec. Especially the original spec of a Douglass barrel.

Unless someone wants a rifle/upper to hang on the mantle. I shoot and use my guns. They get dirty, scratched up, and parts wear out. The primary purpose is function, and as long as the form doesn't look to butt-ugly, I don't give a crap what it looks like.

I use an 18" AR-15 for competitions that (1) don't allow a 20" barrel rifle or (2) when I want to save a little weight over a 20" rifle and (3) when targets are far enough that a 16" barrel won't be competitive. The shooter is often humping -- sometimes running with -- the rifle for extended distances with such competitions.

My 18" started out as a stock Wilson Combat Recon Tactical. A2-ish stock, no BUIS, birdcage FH, Harris bipod, with NF 2.5-10x glass. Over time, things evolved.....
- The A2 stock was replaced with a Magpul UBR. I shoot rifles with a Magpul PRS better, but wanted a collapsible stock.
- Wilson's grip became a BCM Gunfighter grip, to more closely match the grip angle of my bolt action rifles.
- The FH was ixnayed for a TBAC suppressor.
- The glass was upgraded to NF 3.5-15x.
- The Harris went the way of the dodo, replaced by an Atlas.
- When the original 1/7 Wilson barrel was shot out, I replaced it with a Bartlein/Craddock 1/7.7. Bare stainless finish -- no more cerakote.
- Wilson's TRIM rail is gone, as they no longer support the product. It now sports an MLOK-compatible rail.
- Now that I'm transitioning to Arca Swiss mounts on my tripod, a short Arca rail plate will soon go on the rail, just forward of the receiver.
- The bolt's lugs are beginning to show a touch of wear, but it's not too bad for now. A JP bolt is on order, and it will eventually replace with Wilson bolt. The bolt carrier is still GTG.

I don't care that nobody's brother-in-law's third-cousin's buddy from high school ever was issued such a rifle. My rifle works for me. It has dinged steel in practice out to 800 yards -- which by the way, is a pretty pathetic "ting" with any 223 bullet at that distance. It has scored hits on 12" plates in competition out to about 700 yards in competition, in Wyoming and Colorado winds. I has produced 100-yard 5-round groups as tight as 1/2" when I wasn't being an ass hat. It has missed scoring zones on targets as close as 5 yards when I was being an ass hat.

Build an 18" rifle/upper to hit targets. Or build an 18" rifle/upper to look like something that somebody used somewhere. Pick your priorities.

Here’s a rifle I ultimately sold/parted out. It’s a MOD 2. As close as mass would allow.