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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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Ya'll got the part number for that Cap?  I can give the part number for the one I just got #55521 $36 plus shipping......................

Double Tap.......................

Where do you see that on their site?

Where it now says out of stock...sold back out within a couple hours of posting that. I was able to order a set thankfully - been checking stock status every evening for a few months so was shocked to see it change on a Saturday evening.

I'm always a day late. Lol.

MSP's "in stock" status is a bunch of BS.
I've ordered multiple items from them that say in stock, and then a day or two later you'll get an email saying it's backordered.
I've had the #22 TRR and TRC on backorder for half a year now, with them.
Don't get disappointed that you "missed out", cause you didn't.

Happened to me too. I kinda stopped shopping there from that ish

2024 clone rifles shoot in PA

Gonna keep that one on the radar.

I ordered a TRC and TRR a few weeks back and I got the TRC. I know at least one other person in here did too. You might wanna raise some stink if they've skipped over you.

Damn, that's an impressive range.

Done a couple night shoots there.  The facility is pretty awesome.

If it wasn't 5 hours away I'd think about it

What would a OG 12th model ops inc bring these days?

Last one sold for $3500 ish on GB.

Good lord.... 4x what I paid in 2012 direct from Ops Inc.

SO glad to see this, I hope my rifle will be done!

I sent em an email, will see what they say.

I should a grabbed the one I saw used in the EE a few years ago for like $1200. But I mean tbh, my AEM5 works great. Is what it is

For sure, the AEM5 is the same thing as the 12th model, just a different mfg marking.  I am toying with the idea of the OCM5 for another build if it is in fact "better"

Some days I wish I could paint this one...I've got a perfect match for the tan and brown that's left on the rail.

Do it. Paint comes off easy if you're not satisfied.

As much flak I'll get for this, Charlie's got a batch of NOS tan anodized TRRs a while back and I jumped on it. Pretty sure it was a one time thing, they said it was a leftover batch from an NSW contract that A.R.M.S. found in the corner of their shop. Whenever I get a grey TRR for my #35 I'll put it to the side and save it for an early Mk 12.

On a related note, has the TRS ever been seen in the field? Love the way they look

Got a response from MSP - "The items on your order have not been in stock. I don't know when these two items will be back in stock."

So someone is full of it...

C'mon bro...more pics of inside that tote



-MSP is off my list of people I buy from, and that's just one reason why. It's 2024, live inventory should be standard.

Want a redacted copy of my order saying it shipped?

Charlies probably just had regular ones color changed lol.

If you're willing! I'll send it over to em and jack em up haha!

Shoot me an email.

I've had issues with them doing stuff like that, mainly old stuff that they say is available for back order that I know for a fact is discontinued. When I brought it up and suggest they remove it from the site so people don't get their hopes up they just hung up and blocked my number.

I have a bad habit of impulse buying stuff when I don't have anything to put them on. I can probably set up like 7 or 8 guns with this stuff. Current priorities are making an M4 for the #50M and a late Mod 0 for the #38 SPR. It's not a PEQ-2-3 but it'll be close enough for now.


I wouldn't put it past them lol. It's a pretty nice color, almost bronze in the right light. The finish is weird too, it's like silky vs the kinda rough texture on normal grey parts.

Wild cloney parts bro. Wild. I say spray it with stripper and see if it comes off LOL. Personally I'd just blast it and alum black it, or a alum Hyde the colty gray

Since we wanna talk about Atlantic Research Marketing Systems........

Can't say I've ever seen someone chop a TRR before, I kinda like it. If you're just gonna mount an MRDS or RMR that's really all you need. Gonna keep the tanodized one, factory FDE parts are pretty rare and valuable. Honestly $68 for this was a steal, considering what Charlie could have charged. Saw one of these plus a wingless TRC sell for $500 on eBay, insanity

Always thought this mod 1 with the chopped TRR on the back of a TS30 looked totally boss.  There’s better pics of it but don’t have one handy.  

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Of course I finally go to buy a MK5HD and Leupold is sold out. Hopefully they get some more soon.

Anyone know where I can get a Badger Mount for not $300?

Edit: Anyone have some pictures with a Leupold MK5HD on it? Debating if I should run the A1 stock or get a Magpul PRS.

I bought my MK5HD from Euro Optics.

Not sure where to get a deal for the COMM.

Pics start here: https://www.ar15.com/forums/AR-15/Official-Mk12-Mod0-Mod1-ModH-Photo-and-Discussion-Thread/118-520524/?page=1113#i8405979

A1 if you want to look the part. PRS gen 2 if you need it to fit your body and face.

I get a deal through Leupold, so I will be waiting for them to restock. A1 does look really good on it, I will stick with that for a bit and see how I like it when the scope comes in.

Anyone have a clue what a Leuopold 67925 with 22H rings would be worth?

They pop up often in the EE for $250-ish.  I picked mine up there for a little less.

Response from MSP after sending them shipment confirmation from SecretSquirell's order;

"We like to ship complete.  We did have TRC's available so we allocated them to orders that would ship complete."

edit to my follow up email;

"The majority of the time, customers don't want one without the other, especially if they ordered both.  For the few customers that just order the one piece, we can fill it."

:eyeroll:

So it looks like I missed out on getting a leupold mark 4 3.5-10x32 about a few months ago as I was able to find them. Midway has some sales on a batch not too long ago. I know they are discontinued but I can’t seem to find them anywhere lol. There is a local shop that has a new leupold mark 2.5-8 x 32 with the mk12 77 gr turret marking and adjustments. If I remember correctly this is the original standard military issue for the mk12. They are asking for $1700. Is this something I should jump on ? I’d probably like to spend a little less if possible for a used mark 4 3.5-10. But if they are not ripping me off lol then i’d consider buying it.  I know there are other better options but for the nostalgia it would be cool to get a standard issue scope.

I bought my new Mark 4 TS30-A2 (2.5-8x36) with the Mk12 Mod1 77gr marked turret for $1,250 years ago - back when they were still in production.

So honestly, considering they're discontinued AND it's a cool Mk12 piece (even though it's technically not the exact same issued scope) - $1,700 isn't that terrible of a price.

I'd at least try giving them an offer for a little less, but like I said, if it's new, that's not a bad price considering the things I mentioned above.

Wish I had further to shoot.

I'd say she's pretty damn accurate.

I'm happy with it for sure

That trace though.

So what they're saying is if you're backordering multiple items you have to make individual orders for each part and pay the extra shipping...

That's how I ended up doing it even though I didn't really mean to. I ordered rings, then remembered a few hours later that I needed the TRC. Then a day or 2 later I realized I could b/o the rail and did so. I emailed and asked about combining the first 2 orders to make it simpler, but they said the TRC was b/o. I get shipping notification of the rings later in the day, then a day or 2 later I get notification for the TRC. I don't think they really know what they've got in stock.

Anyone have experience with getting stripped gas block screws out? Got the first one out no problem, but second one is stripped. My CLE Douglas barrel finally came in, so I'm taking apart my upper to rebuild it and looking to sell the barrel, so don't want to scratch it if I can avoid it.

I tried using one of those damaged screw extractors, but it wouldn't extract.

Looks like your down to just drilling it out now based on the amount of material I see left.  I would go slow and drill that bitch out the rest of the way........

I figured as much haha. Thanks for the response. I'll put the drill bit down in the other hole to see how deep it goes and then set a piece of tape to mark it so I don't go too low.

Got a surplus A1 stock along with a surplus A1 grip from my friend, thinking about changing out the ergo grip for it.

Sold my MK4, now to wait for Leupold to restock the MK5HD. For the Badger mount, what would be a better choice, 0MOA or 20MOA?

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