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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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Atta boy

Edit: page ownage. MK12 mod 0

Is that Core or Altus or whatever they changes their name too?

doubled

Nightforce A107. Clone correct for a Holland, no levers, only a few dinars more. It's only money...right?

This, love my A107s. Can be found cheap on the Bay too.

My preferred shooting spot for going beyond the ~250 yd at my parents' place, love it there.  A little over a month ago I was reminded just how much temperature plays a part in external ballistics  It took me a few LOW misses w/ CBC 77gr to remember I hadn't factored in the 40 degree temperature drop since I was last there.  After correcting that, 700 yd was easy again.

WOW

Yup. You local?

That's what I currently run.

Yes.  Live outside Milton, just over Garçon. Lived in Navarre for a long time. Work in Escambia.

I think it's finally complete.

Needs a Colt AF or an Armalite upper

This is all I gots. I'm not sure that it's time period correct...

Believe that upper would be anachronistic, but if you decide to swap it in I'll send you a GM teardrop foward assist to go with that lower.

Very generous sir. I think I'll keep it square forged for now. It shoots well, I'd hate to mess with the mojo!

... unless the Armalite would give it special SPR powers...

Y'know, I swore I wouldn't get a "correct" upper for my 6.8 Mod 0 because it was just a forge mark and the thing shot great...  Mine was a square forge too before it wound up with a C AF.

At any rate, if you should end up changing it out just yell at me.

Swapped some lowers around between the rifles and resulted with this. The Mk12 is my favorite stick in the safe, so I had to give it a lower by my favorite company. Brownells name on the side just never reflected this gun as a whole, even if it was the correct A1 profile

I mean, you'll have to replace the barrel with a Douglas at some point too, no? Might as well snag an Armalite off a used upper from the EE and part it back out, get CLE to do a douglas perfectly profiled for the original FSB and long collar, and booooom. Perfection.

LOL. Yeah, I saw your pics in the Holland thread after posting. You have one bad ass looking H.

Don't downgrade the rings.

No plans to. For nostalgia sake, I do kinda want a pair but the smart part of me says no.

I have some ARMS #22 Medium with original no lever stops in the EE. I impulse bought them a while back thinking I would do a Mod 0 Clone. Other builds have taken a priority.

I will price drop for a fellow Mk12 dork.

Hey guys, I'm a big Mk12 fan, had a couple at one point. So, I'm always have an eye out for Mk12 things. I was at a local shop today and he had an interesting scope in his case. It was a Leupold TS-30 A2, but it was and early one. It was a 3-9x36, it had a mildot reticle. Glass was ok but it did have a ring of epoxy of some sort on the side. I don't know what the protrusion on the side is it's not on the newer ones. Just thought it might be of interest to you guys as it seems to be a really older version.

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PM sent.

Hide your dogs

Weren't those tags used as some form of inventory control for the military? Not sure I'd risk the cash on something like that.

Sure looks like USGI inventory ID tag was there.

That’s not to say that the scope wasn’t disposed of through DRMO channels. Typically, that class of supply is coded for destruction, not for sale to public.

Potential buyer should proceed cautiously.

I just spoke to Leupold tech.  He verified that it's not a fake but couldn't tell me if was legit as far as being released into the civilian world or had fallen off a military truck.  I then spoke to the owner of the shop who has the scope.  He said got it in trade with several other items and doesn't know the history.   I told him I was interested but wanted to do some more research on if it's legit or not and would call him back in the morning.

Anyway to verify if this is still property of Uncle Sam?

Haven't seen you for a while

That epoxy in the photo is consistent with that used to surround UID tags. It’s a fair chance that scope was Gov property at one time. Hard to say if it was disposed of through proper channels or not.

Since it’s no longer an issued item, I doubt anyone is looking for it, unless it was stolen and registered with CID, etc. It’s pretty widely known that ACOGs come up for sale with USGI origins and Trijicon will confiscate them if/when they are received for service.

Leupold should be able to tell you it’s origin by serial number... unless, perhaps, it was purchased with unit funds and not via contract. Bottom line it’s a cool piece that would be awesome to own.

I'd buy it if the price were low enough with the expectation that I'd likely never send it in for warranty/refurbishment.

Samesies.

The epoxied 'dot' is called a 28 Kbps Contact Memory Button (CMB). In use about 2002 - 2008 time frame. They were used primarily to issue equipment. They were short lived and didn't work well.

These were not RFID. They used a handheld reader that had to actually make contact with the chip in order to read it. They were easily damaged and often would not work.

I be around brah! Upper looks great!

It's actually a little disheartening, I got my upper built by kevin when they were supposed to legalize hunting with semi-auto 3 years ago. It didn't happen, this year they denied it again. I'm gonna end up having to get rid of this thing. Y'all are some lucky MoFoes

Why get rid of it?  Keep it and shoot it.

This

Looks good

Anyone else done their own "etching" on 80% and/or brownells lowers?? I've got a few more 80%ers I need to complete and am thinking this is the route I'm gonna take. I need some motorvation.

I keep wanting to try it.  There's a place you can order the pattern's from but I can't remember who it was.

Dogfight Ink

So you're going to get rid of a gun because you're not allowed to hunt with it? What fuddfuckery is that? Very few happy Mk12 owners including myself actually hunt with these.



Grabbed the BUIS off the EE. AEM5 next. Has just been hard to justify since the Omega is such a good can.

Thanks.  That was it.  Now only to find some decent priced A1 80% lowers.

Tactical Machining has been my go-to. Would get "blem* lowers for $30. However, it's been a while since I've bought anything so no idea on price and availability.

to be completely honest, it doesn't fit what i normally shoot. I have mid-long range bolt guns and shorter range semis. I'll probably still give her the old college try here again, but what i actually bought it for seems to be a pipe dream anymore.

Gents,

Life happens and subsequently, I just listed my SPR with a lot of old parts. If anyone is interested let me know. I may be able to work with some of the purist in here on price. Price is high, I know, but maybe it will help me to not sell it.

SPR

PA is such a backwards state when it comes to hunting.  i've been wanting to build a 6.5 creedmoor AR to hunt with and every year the game commission says "we are considering allowing semi autos for big game" and they keep shooting it down just after all PA hunters start to get hopeful.

So what’s the clone correct sling adapter/attachment for an A1 stock?

Just scored a TAS-1 off the EE. Slowly finishing out this deployment case.

The TAS-1 UMSS came with a buttstock adapter, an Eagle A1/A2 stock adapter should be the same.

I've bought all my 80%'s from TM, but they've been out of stock for forever now

Awesome thank you.