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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.


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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


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

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Attached File

That was my point.







Gen1 or enhanced?

Either one, as long as it fits on a buffer tube and isn't one of those Gen 1 stocks that needs sanding inside or doesnt fit on the buffer tube.

 

I still have the gen2 that I took off of my mod0, if your interested.



I'll shoot you an IM when I get off work.

Finally got stuff torqued down. Last is my brake. How are you guys wrenching them down? How is it timed right the thinner portion is at about the 10 o'clock right now. Don't want to mess this thing up.
http://img.photobucket.com/albums/v633/mrwhite182/IMG_20140321_164319_619_zpssgu1xgtp.jpg
Haven't even finished my first and started scrounging parts for a second.
http://img.photobucket.com/albums/v633/mrwhite182/IMG_20140321_155928_406_zps3a07lfmc.jpg

I used an adjustable crescent wrench on the flats. I precrushed a washer until it was just under 11:00 when hand tight.

If you do it that way, tape the flats. I didn't bother doing so and it shows.

Roger, so does the thinner flat go to the 12 or 6?

12

Appreciate your help and time sir.

who has the MK12 Mod 1 block as shown in previous pic ?

Whatever do you mean, capt'n?



 

Navy SEALs MK12 Mod 1. Took this picture at the Miramar Airshow several years back.

That is sweet.
I was a Miramar Navy brat

At first I thought the pic rail up front had been milled down and then I realized it was where the front sight was when they painted it

Anyone know what reflex sight mount that is that mounts to the top of the ARMS rings? Doesn't appear to be the TRR.

Those are NF rings with a wilcox mount that replaces the top half.
As a side note, it's another "legit" mk12 with a type-D stock.
 

Good catch. And a mod 1 this time.

Those are some low rings!

Way too low for my liking. And is that an NSX 1-4x with a Doctor? I fk'n dig that setup. Would be boss on a Holland...





 

 

If anyone is looking (like I am) for the black KAC front sight and want to pay an arm and a leg for one: http://www.ebay.com/itm/knights-armament-sight-KAC-Sight-MK18-MK12-KAC-P-N-99051-/141229192481?pt=LH_DefaultDomain_0&hash=item20e1ea7521

where can you get one of those ?

Just snagged one (1 left) - http://tradingplacepawn.com/knights-armament-front-flip-sight.html
 

Badger Ordnance NAVSPEC Mk12 gas manifold?



 

Badger block @ Brownells

This one? Maybe it takes ninjaing to get one with the NAVSPEC package?

It's the parkerized one. Midway has the as well.
ETA- To be more specific, The parkerized one has the NAVSPEC on the box.

Picked it up off eBay, right around 40$ shipped.

Tell ya what, I better get one of the PRI early tube runs. Already missed the Knight's rails on BCM, no money for ARMS non-leverstop #22's when they popped up, missed the original Geissele SMR's with the oval cuts, the cheap M16A1 parts kits, now it looks like Noveske is cutting the Crusader 12.5" barrels out of the lineup. Even if I start having more spending money here in a few months, the things I'd want to spend it on are unobtanium. Oh, and NDS is abysmally back-ordered on M16A1 pattern lowers as well. Lets just add the new restrictions coming on all Russian made ammo and guns coming in, so nevermind scoring one of the Arsenal AK-74s built off the Izmash receivers, or cheap steel 5.45 to go with it. WHEEEE

Basically I've traded all the AR goodies I'd really wanted this last year for a baby. I'd never trade the baby, or re-do things differently, but damn this sucks. I guess I at least haven't had something come up that would make me sell my Mod0 project off. There are still good things at least.

ON TOPIC now, I still can't get the LMT staking job on the carbine stock to let go. I really want to put the A1 stock on and an A2 grip to at least add some more spec points to offset my can.

And just to double check, do we really only have like 3 Mod 0's with GEN III tubes in the wild pictured?

1) 2 Pics of an operator in Iraq, old style desert cammies on the first page. A1 fixed stock, A1 grip, looked like Leupy 3-9x36, PVS-22, Harris on Knight's adapter.
2) Pic of AF operator in helo, Type D A1 stock, 3-9x36, Harris bipod, A1 grip.
3) Pic of an Army? dude in back of truck with GenIII rifle, looks like Iraq. A1 Stock, A1 grip, 3-9 scope, Harris bipod.


There is one pic I labeled "unverified" on DemigodLLC's blog, but it looks like it would be a legit rifle. Again an A1 stock, A1 grip, 3-9, and Harris bipod. Seems like these pattern guns were fewer and all deployed in basically the same config. This probably lines up with the timeframe that the Mod 1 was fielded based of LtCol Lutz's input on it being due to PRI not being able to supply enough handguards and FSBs. Basically I think the Gen III equipped guns were the last batch that came out of the Mod 0 config, after the Mod 1's had been fielded but before Crane decided to only field the Mod 1. Makes sense, they probably found the Mod 1's much simpler to produce, probably lighter as well. No FSB or ARMS sleeve to deal with.

If any of you guys know of other LEGIT Mod 0's with the Gen III tubes in pics, please post them?

I would do it, but I'd be shunned from this thread.

If you already have a Mk12 Clone of some pattern, posting a Mk12K type gun alongside it wouldn't be an issue, at least to me. Just make sure it's chaperoned properly by the Mk12 clone in any pics, as to show you aren't a random dude trying to pass off a non-clone rifle or an interpretation.

Why's that? As long as it's a legit Mk12 employed by the .mil I don't see the problem. SEAL Mk12s commonly used NF optics and rings, right?



 

Get a Hammerhead stock wrench.  There is no staking job they won't remove.

Also, I ordered several NDS lowers on Tuesday, they emailed Wednesday and said they stock to fill the backorder, maybe they have some left?

While I completely missed the rails being in stock for 17 minutes I might have found a temporary solution.

Someone suggested a few pages back that armalite has a rail that could be passed off on a Mk12 mod 1 if you squint and look at it from 20 feet.

Link

I think I might do that for now until I find one of the KAC rails to replace it. Thoughts? the barrel nut (not sure what its called) looks fairly similar. And with some 11 rib KAC panels on it I think it'd be an OK temp solution.

Contact Wes Grant [email protected].  He has them in stock.

That is close.  I've never seen that one before.

The parts between the rails are flat and not curved like the KAC but it could be an alternative.

drkhrs2 - who is that email for? Do they have a website?

MSTN in Mid Southern Tactical network.  They've been around forever, but the website is down for construction.

I know Wes sells a lot on Gunbroker.  He has a rail on Gunbroker now.

I think that is the elusive 2.5-10x24 compact. Not sure about the cheekweld, but it's damn sure low-profile.



 

Any issues with the Badger Ordnance MK12 gas blocks?  Would it be spec for a MOD 1 build? It would be nice to pay $60 for the BO gas block vs KAC's $107.

That's what I used for my build.



 

I used one for mine, but the ID was very tight.  Needed to be honed to size.

Yeah, I've heard some fitting might be required on BO gas blocks.  Heck, I can only get my OPS Inc. collar halfway on my HCS barrel by hand.

Mine was WAY tight as well.



 

Wes has three rails left if anybody needs one.

I spoke with him via email just a bit ago and told him I'd take one.

He said he sold a few in the past 1/2 hour, I think your was one before the three.  Good score though!

I have used 2 of them and they went on perfect.

Guys,

This thread moves quite fast so I'm not sure everybody caught it, but it seems Nodak has some A1 style lowers available.  I ordered a couple on Tuesday, received an email on Wednesday, and they're in shipping now.

Their page says backorder only still. Where did you see this?

I just called them and ordered over the phone cause I couldn't figure out if the website would let you put them on backorder.