* * * * * * * * * *

The following parts lists and substitution parts was compiled by lancecriminal86 over the course of a LOT of research. Read up and pay attention!

Below are the 100% .mil-spec parts lists to build a true SPR or Mk12 clone. Some of these parts are no longer manufactured and will require much effort and money to locate through forums and online brokers. Keep in mind the rifles were built off donor M16A1s, hence the prevalent A1 parts in the lower receivers and the BCGs. They were also first configured using parts available from 1998-2004, and most are inferior in some ways to newer designs. If this bothers you too much, STOP NOW.

The rifles were issued as a kit in a Pelican 1700 case with cutouts. The kits included the rifle with suppressor, optic, bipod, an Eagle TAS-1 UMSS sling (unobtanium and also absolute crap), with a Dewey 1-piece cleaning rod plus Otis cleaning kit, and a cutout for magazines. An operator's manual was also included, however these have not been officially released for public consumption. However, the manuals are out there, and some companies building Mk12 uppers include one. Whether these are official .mil operator's manuals or specially made is currently unclear as the manual itself still contains language that it is not for distribution.

- Alternate .mil-spec parts due to NFA, NLA parts, or changes in name/markings for current production in [brackets]

- Extra notes about parts or availability are in (parenthesis)

LOWER
Lower receivers were standard across the SPR/Mk12 variants and the only variations would be between grips, stocks, and buffers. Most were marked either Colt or GM Hydramatic. All other parts were the same in regards to the lower parts. One caveat is the trigger, as the program originally selected the Knight's Armament 2-stage Full Auto Match trigger. Later on, some issues regarding negligent discharges occurred, and Geissele SSF triggers ultimately found their way into the Mk12 family. Whether 100% of all Mk12s eventually received the Geissele trigger isn't clear, so either is acceptable.

• Lower: M16A1 pattern [Nodak Spud NDSA1 or 80% re-profiled/finished/engraved]
• Trigger: Knight's 2-Stage Full Auto Match Trigger or Geissele SSF [KAC semi-auto Match or Geissele SSA/SSA-E]
• Grip: A1, A2, ERGO Original
• Stock: Originally issued with A1 stocks, both solid D and trapdoor E types; as A1 stocks dwindled, A2 were used; ModH rifles rebuilt with Ace SOCOM stocks
• Small parts: Standard M16A1 parts
  
  

UPPER
The upper receivers, which ultimately differentiate the four variants of the Mk12, have the most variation between each other.


Early SPR/Mod0

• Upper: Colt, Diemaco, or Armalite marked, flat top, M4 feed-ramps
• Barrel: Douglas 416r SS, 18" SPR contour, 1/7 twist, flats milled for PRi FSB (Compass Lake, Centurion Arms, High Caliber Sales, and PRi can all supply barrels that meet the appropriate spec minus FSB flats)
• BCG: Colt M-16
• Handguard: Precision Reflex Gen I carbon fiber free-float Handguard, rifle length (identified by button-head screws and one vent hole near barrel nut on lower half; no heat shields)
• A.R.M.S. #38 SPR MOD Sleeve (either the PEQ version or with uneven spacing on the front  but not the full 1913 railed version)
• FSB: PRi early folding front sight base and gas manifold, set-screw, with elevation wheel
• Charging handle: PRi Gas Buster M-84 with military latch
• Muzzle device: OPS Inc 12th Model brake/collar, and 12th Model suppressor [Allen Engineering AEM5 and brake/collar]
• Rear iron sight: A.R.M.S. #40
• Scope rings: A.R.M.S. #22 Medium rings, #22 Tactical Ring Cap and #22 Tactical Ring Rail (rings should not include "lever-stop" hump as produced later by A.R.M.S.)
• Optic: Leupold Vari-X III 3.5-10x40mm LR, M3 turrets, illuminated Mil-Dot reticle (use .308 turret) [Leupold LR/T 3.5-10x40 LR, M3 turrets, Illuminated Mil-Dot reticle]
• Bipod: Versa-Pod with A.R.M.S. #42, or a Harris with A.R.M.S. #32 (Versa-Pod far inferior to Harris)

Late Mod0

• Upper: Colt or Diemaco marked, flat top, M4 feed-ramps
• Barrel: Douglas 416r SS, 18" SPR contour, 1/7 twist, flats milled for PRi FSB (Compass Lake, Centurion Arms, High Caliber Sales, and PRi can all supply barrels that meet the appropriate spec minus FSB flats)
• BCG: Colt M-16.
• Handguard: Precision Reflex Gen III carbon fiber free-float handguard, rifle length
• A.R.M.S. #38 SPR-PEQ-2-3 Sleeve
• FSB: PRi folding FSB, set-screw, .750 (original production had PRi's full address engraved on sight tower; those engraved with "PRi USA" are later manufacture)
• Charging handle: PRi Gas Buster M-84 with military latch
• Muzzle device: OPS Inc. 12th Model brake/collar, and 12th Model suppressor [Allen Engineering AEM5 and brake/collar]
• Rear iron sight: A.R.M.S. #40
• Scope Rings: A.R.M.S. #22 Medium rings (rings should not include "lever-stop" hump as produced later by A.R.M.S.)
• Optic: Leupold 3-9x36mm TS-30, Mk4 MR/T 2.5-8x36mm TS-30A2, M2 turrets with Mk262 BDC, illuminated TMR reticle
• Bipod: Harris with either A.R.M.S. #32 or KAC RAS bipod adapter

SPR/A, SPR/B, Mod1

• Upper: Colt or Diemaco marked, flat top, M4 feed-ramps
• Barrel: Douglas 416r SS, 18" SPR contour, 1/7 twist, flats milled for PRi FSB (Compass Lake, Centurion Arms, High Caliber Sales, and PRi can all supply barrels that meet the appropriate spec minus FSB flats)
• BCG: Colt M-16
• Handguard: Knight's Armament M4 Match FF RAS, rifle length (now called the SR15/16 Match FF RAS)
• Gas block: NSWC Crane pattern (Badger Ordnance parkerized/NSN version is correct, has open front of gas tube hole)
• Charging handle: PRi Gas Buster M-84 with military latch
• Muzzle device: OPS Inc. 12th Model brake/collar, and 12th Model suppressor [Allen Engineering AEM5 and brake/collar]
• Scope rings: A.R.M.S. #22 High rings (A.R.M.S. rings should not include "lever-stop" hump as produced later by A.R.M.S.)
• Optic: Leupold Mk4 MR/T 2.5-8x36mm TS-30A2, M2 turrets with Mk262 BDC, illuminated TMR reticle or NightForce 2.5-10x24 (optionally with NightForce rings)
• Bipod: Harris with KAC RAS bipod adapter (BRM-S, A.R.M.S. #32 could still optionally be used)

ModH, Mod "Holland"

• Upper: Colt or Diemaco marked, flat top, M4 feed-ramps
• Barrel: Noveske 16" Recon, mid-length gas system, profiled for OPS Inc. 12th Model brake/collar (will require aftermarket contouring of most barrels)
• BCG: Colt M-16
• Handguard: Precision Reflex Gen III carbon fiber free-float handguard, FDE, rifle length
• Charging handle: PRi Gas Buster M-84 with military latch
• Muzzle Device: OPS. Inc. 12th Model brake/collar, and 12th Model suppressor [Allen Engineering AEM5 and brake/collar]
• Scope Rings: A.R.M.S. #22 Medium rings on PRi recce rail (rings should not include "lever-stop" hump as produced later by A.R.M.S.) or LaRue LT-104 SPR mount
• Optic: Leupold 3-9x36mm TS-30, Mk4 MR/T 2.5-8x36mm TS-30A2, M2 turrets with Mk262 BDC, illuminated TMR reticle, Leupold Vari-X III 3.5-10x40mm LR, M3 turrets, illuminated Mil-Dot reticle (use .308 turret) [Leupold LR/T 3.5-10x40mm LR, M3 turrets, illuminated Mil-Dot reticle]; S&B Short-Dot
• Bipod: Harris with either A.R.M.S. #32 or KAC RAS bipod adapter
• Iron sights: (apparently PRI were supplied but never used)
  
  

In the Wild
Naturally, once these rifles were issued to units, operators and even Marines used various non-issued parts. Here is a short summary of what has been seen:

Early SPR/Mod0:
Both Leupold 3.5-10x40mm and 3-9x36mm scopes have been used. Many have had carbine stocks like the old CAR-style, enhanced M4, SOPMOD Gen I, or even the Tactical DuoStock swapped on.

Mod1:
One 3rd SFG-issued rifle pictured with SSgt Robert J. Miller (MoH recipient) used an A.R.M.S #36 S-EX 5.56mm rail, and a Leupold M3X 10x fixed-power scope, possibly pulled from an M-24 or SR-25 rifle. Another has been seen with a Magpul PRS, LaRue mount, and a Premier Reticles 3-15x used by an AMU shooter, and a similar rifle was pictured on a FOB in a very posed-looking photo. Further, a USMC-issued Mod1 was seen using #22 Medium rings instead of High rings, and a LaRue mount has been spotted as well. Grips have varied from the usual A1, A2, and ERGO, and at least one Magpul MIAD has been used. As with the Mod0s, carbine stocks like the SOPMOD and M4 have been used on Mod1s.

ModH:
The Mod "Holland" was already a small-batch configuration, but even as soon as they were issued to 5th SFG units, some Ace SOCOM stocks were replaced with Magpul ACS and CTR stocks. Optics are basically anything existing in the unit's inventory, from S&B ShortDots still in the system, the 3-9x and 3.5-10x Leupold scopes from earlier Mod0s, and there's even a photo of an ELCAN on a Mod1 floating around. No non-magnified optics like EOTechs or regular Aimpoint M2/M4s, but Micros have been seen on offset mounts. Backup iron sights, as a whole, were almost entirely left unmounted. Grips were again the same usual selection.


Parts Alternatives for Clone Building
Many parts are rare, expensive, and/or both. Despite this, there are some alternatives to a 100% pure clone that will still provide the same visual look and performance. While not a museum-grade clone, most would be hard-pressed to discern the difference. Just know there are those of us out there that will haze and peer-pressure you into further moving your build towards a true clone.

Barrel:
Popular options are the White Oak Armament SPR barrel (rifle gas), BCM's SPR barrel, Rainier's Match and Ultramatch offerings (ensure it's the SPR contour with 12th Model profile), Ballistic Advantage's SPR barrel. Compass Lake Engineering can also spin a Mk12 profiled barrel with a Criterion chrome-lined blank, or even a Krieger, which was one of the original contenders for the program. The DPMS Mk12 barrels are NOT properly profiled for a clone.

Optics & Rings:
In the case of the Leupold 3-9x or 3.5-10x, it's generally okay to go for a non-illuminated version of either, sometimes with M1 or other turrets and reticles. As far as the NightForce scope, the 2.5-10x24mm is not generally released to the public anymore (with one recent exception through Sniper's Hide), so many use the 32mm or even 42mm versions with the #22 High rings. As for the rings, any of the recent produced A.R.M.S. #22s with the lever-stop humps are functionally the same, the desire for non-lever-stops is purely aesthetic when going for the most authentic look. As LaRue LT-104s have been seen in use, it is justifiable to use one depending on whether you have a specific rifle you want to copy, or even just if you absolutely cannot acquire #22 High rings.

A.R.M.S. #38 SWAN Sleeve:
The #38 family of sleeves are no longer available. Finding them secondhand usually cost $250-$300 easy, more for rarer early variants. Fortunately, PRi's copies of the sleeves look and function almost identically, with minor visual differences. PRi and other builders supply these currently for complete Mod0 builds.

FSB:
While the set-screw version of PRi's FSB is spec, most use the cross-bolt, clamp-style version. They are extremely robust, and when aligned and torqued, have been shown to hold strong enough that you'll probably shear your barrel extension pin or upper before it budges. This is mainly how Mod0 uppers are supplied by most vendors, including PRi themselves.

Suppressor, Brake/Collar:
Diverging from the OPS Inc. or AEM brake and collar will get you MAJOR flak. Trust me, I've been running an AAC SPR/M4 for years now and it took a LONG time to not get clubbed every time I posted it. The Allen Engineering AEM5 is basically the current production of the OPS Inc. 12th Model, as they were originally made by Ron Allen and his team in the first place. Only minor differences separate original OPS Inc. cans from AE cans, and these are only obvious to trained eyes.

As far as the rest, you can swap Colt parts out for any other .mil-spec parts, like BCM, DD, CMT, etc. Any billet uppers/lowers, funky BCG coatings, extended bolt releases, etc. are extremely frowned upon. Remember, once you start going down the path of building a "better" rifle rather than what was spec, you're quickly beyond clone territory and would have been better off building a custom 16" or 20" rifle. Cloning is generally viewed as all-in or not at all.


* * * * * * * * * *

Complete Mk12 Mod0 / Mod1 Uppers
Bravo Company Manufacturing
High Caliber Sales
Precision Reflex Inc.


Specific Mk12 Tech
Augee's side-by-side comparison of the original ARMS SWAN Sleeve and PRI reproduction PEQ Sleeves: bottom of p136
KOBK's side-by-side comparison of PRI Gen I, II, and III handguards, and Gen I and Gen II FSBs, and SWANs: middle of p137
Augee's Mod1 gas block tech: top half of p357
Glass1's Early Mod0 photo breakdown: middle of p449
tamboi's Leupold Vari-X, TS30, and TS30A2 scope history/lineage, and part numbers, p.792


* * * * * * * * * *

As of 16 May 2024, Ron Allen is still making custom parts for his suppressors:

* * * * * * * * * *


Attached File

That's the way these things typically work out.





No progress for weeks, and then all of the shit falls in line at one time.









 

Got some descrepencies but a cool pic i havent seen before.

 

 
Also to add, unless you've been issued a Mk12 as your primary weapon, secondary to your Mk16/M4 service rifle, you don't have a lot of room to talk.


 

Just FYI for those stuck on slings. We used almost every decent 2 point on the market. I used an Ares Armor husky, a lot of vcas and vtac slings. I also used the butt stock adapter from the old specter sling I had back in the day.

Gentlemen, I am almost finished with a replica of my deployment M4, Anastasia and since I have terminal BRD, I am planning out my MK12 build. Was planning a Mod 0 but Gaston4s Mod 1 shots convinced me to go that route. The KAC FF RAS is hard to find so would the LaRue 12" be an acceptable spot holder until I can source one? I have the a1 stock, Harris Bipod and I am planning on sending my 80% lower to braceman for a reprofiling.

They are not hard to find. In fact, Operation Parts has them for pre-order.

http://www.operationparts.com/knights-armament-long-ff-ras-mk12-mod-1/

The LaRue would be functionally identical, but a true Mod 1 needs the KAC. Although, you could use a LaRue on a recce but that's a different issue.

I decided to straddle the issue. "Correct" Eagle buttstock adapter, KAC front sling stud, and Eagle hardware/HK hook from a TAS-1 I used to have. Just decided to use a different sling itself since I cut up the Eagle.

As far as 3 points go, they work well when you aren't concerned with shit like another person grabbing your rifle and having their way with you, or getting hung up on all your gear on your chest. So if you're hunting or hiking out to a shooting spot, it's handy and not unwieldy. Not so great if you are getting in and out of trucks or doing CQB.

Cmcflex, thank you for the lead. And they even have links to the other Mod 1parts they have. I definitely agree with you about the KAC necessity. For some reason I thought KAC was holding off on making them available like DD with the RIS II

Also check the EE.  There have been a few for sale lately.  While some of the sellers are stuck believing they have an "out of production, rare item" there are some in touch with reality and asking a reasonable price.

So according to PRI, the Gen I with set screws predates button heads! Now I'm conflicted on even painting it.

Anyone know a good clearcoat that I can rattlecan over and strip while protecting the original finish?

 
Paint is a clear coat with pigment

Did the gen. 2's not have button heads...

Gen IIs did not, and I don't believe any made it on .mil guns. They used set screws

Here's his full reply:

"That is a very early version that was before the button heads where added for strength and keeping forearm locked.  Keep it assembled there is lead shot under the set screws pressing against the threaded part of the barrel nut to protect the threading."

Cool.

done, what do you think?

Well.....I think I want your A4 clone.

Mod 1 looks good too man.

Awesome!

I understand the correct TS30 may have ITAR issues, but I think the 2.5-8 Mk4 would look better. But you've got most of us here beat with your lower alone. Outstanding job for getting one together outside the US.

Looks damn good to me.



       
Ain't nothing wrong with a 3.5-10 on a mod1.













 

 
An A1 lower.....BRAVO! Looks wonderful.

Can't remember, his is a legit fully ottermatic Colt A1 isn't it? I thought maybe it was an engraved false third pin, but seem to vaguely remember him having a legit Colt A1 lower...

Yes plz. Also, pretty interesting dude in the bottom pic has his 99051 mounted on the right hand rail

Thanks!
Yes it's an original 1971 Colt m16a1. Only thing it lacks is the "us property".
It doesn't shoot full auto no more and it's only semi right now.

How come? Do you have to throw a semi auto selector and fire control group in it to keep it legal there or what?

 
Appears to have a sear block in place.

I added some new unused parts in the AR15 Parts - New - Upper Receiver section

How the fuck do I keep missing those pics. Goddamnit. My photo archive needs a total re-work, again.

I do wonder if that was a Marine purchasing his own, or if those were snagged from an M14. Looks like the same guy though in both, same sling, scope cap layout, MAgpul 20 w/bottom. Looks like his rear KAC 600 is under the middle of the scope, between the rings too. Guess it wouldn't clear the eyepiece.

Had we decided those were Medium rings too? I now recall this one being discussed. This and the one with a LaRue were the two USMC call outs in the past for new "kosher" parts.

Go check the replies.

#22M's and yes, it's the same Marine in both pics.



I may start a dropbox for all the mk12 pics I've saved. If I do, I'll send you a link. I may have some that have been deleted elsewhere.



 

Me votes we should do it like the CQBR thread and have Utah add the pic library link to the OP. Let me know if I can help with anything, I'm sure it's an ass load of pics.

61 68 currently. Most are "in the wild"/end user, however, there are a handful of some personally owned gen1/2 PRI uppers that have passed hands over the years.
There are some more that I need to save just in case anything happens to someones hosted files.
 

 
Works for me.

If he's alright with consolidating everything, I'll send the Dropbox link to LC and let him take it from there.



 

I accept. Google's image search helps too for bigger sizes, uncropped, context, etc.

There should be a FF RAS in later this week so I can transition this thing into a Mod 1.

What barrel you going with? Dangerdan has a nice brand new WOA in the right profile up In the EE along with a collar.

ETA unless your barrel has the collar step in it. Can't really tell in that pic.

Keep the rainier barrel. I'll worry about the brake later. This is a back burner project and I'm also not a super cloner so it'll work well enough for my needs.

I was just thinking for you to mount the collar. I think the true SPR profile barrels have a collar step that helps the set screw hold it in place, can't tell if your barrel has it or not. But a Mk12 without a collar would go over like an 89 civic at a muscle car convention around here.

One WOA SPR barrel getting ready to head out!

Craniums up for the NE Florida Mk12 Mafia.  I'm planning on being there with my Mod H.




 

Niki

No you don't. Had to carry one of those fuckers in Iraq

Merry Christmas to me! I am stoked bro.

Squirrel, yes I do. I've wanted an A4 clone for years, I just don't want to actually pay for it. Not that I could if I wanted to.

Kinda along our conversation the other night: I've even got the parts clone my issued A4 except the barrel too

It always comes down to having everything but the barrel doesn't it? If it wasn't for LanceCriminal my Mk12 would also have everything to be a functioning rifle, except the barrel.

Random thing I happened on while digging up higher res pics. Back on Pg. 340, user Stukas87 had posted a photo of himself with an early SPR along with a CPT Fiscus (RIP). I remember SWM or someone pointing out that he was a user here when I reposted it, but just now went back over the actual initial post and saw the context.

Even more intriguing is that he states he was using an M4A1 lower in the pic. He also expressed that the A2 was too long hence the use of an M4 lower, and that other guys were doing the same. While I'm curious if he mixed A2 for A1, I'm even more so if that's further proof from back in 2014 that M4A1 lowers were being used. The rifle is canted so there's no visible way to prove it's an M4 lower, or if it was meant that the carbine extension was swapped on request. I'd just as soon takes his word though that it is indeed an M4 lower. And with that PVS-17 on there, I guess the loss of match trigger for NV capability wouldn't be such a huge issue for that specific use.

Which ergo grip is everyone using?

If you zoom in on the rear of the lower receiver, it appears to have the A2 reinforcement.






 

 

I'm tired as fuck

Here's the first cut of the

EPIC GLORIOUS MK12 PHOTO ARCHIVE OF AWESOMENESS

There are definitely holes, I know of more pics from some of the "photo shoot" looking ones, some more of Mod 1s on display on tables, and various USMC pics from some of our gents in this thread. Also missing some Mod H stuff too.

Next stop, captions! Organizing! Chronology!

Looks good.



There's one pic of a mk11 barrel/suppressor that needs to be snipped though.



 

 

I just want to thank you.....






For including a pic of the glorious Mk13 master race.