* * * * * * * * * *

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

Do you have an AEM5 in the works?

Have a backorder in with DSG, currently in month 5 of backorder

rolled the dice and grabbed an "in stock" set of A110s off optics planet

got the dewey rod in and swapped back to the A1 stock in anticipation for the x24

one last pic with the x50

Never had any interest in a deployment case. Went to the range yesterday and had too many rifles, not enough cases. Now I want a deployment case . Are there any places still selling the cases?

Easiest way to get a mk12 specific case is probably just reproduction foam insert. I stumbled across some Navy M110 (mk11 Mod2) 1700 cases locally over the weekend that have a very similar layout to the MK12 mod0. Not clone correct for the MK12 obviously but it fits nicely and is cooler IMO (and cheaper) than getting reproduction stuff.

That will probably be a hard thing to fulfill now, might be best off to buy a 1700 new with solid inserts and get yourself an electric filet knife and cut it yourself. Otherwise look around gunbroker or the EE, but expect to pay a couple bucks based on what I've seen

I kinda figured this is the route I'd have to take. I have no problem cutting foam. Was just hoping to get a used 1700.

Mk12 crowd was asleep at the wheel yesterday.  Larry Vickers' Mk12 Mod 1 sold on Gunbroker.  If you zoom in on the scope you can see that the bottom is marked RECON NAV-SPEC.  This is also the same upper photographed in the AR15 Volume II book and used in this video.  

https://www.gunbroker.com/item/897183067

https://m.facebook.com/VickersGuide/photos/a.946297822125293/1806238502797883/?type=3&locale2=fr_FR

https://youtu.be/uTEhO79ip-s

We were all out shooting our mk12's

Were Armalite upper receivers used on Mod 1's, or was that limited to the Mod 0's?

Attached File

Attached File

Attached File

I appreciate it. I've seen those pictures before but never noticed the Armalite forge code.

I got a delivery confirmation but won’t know how it is until I get home from work, keep my expectations low and I won’t be let down I guess🤷‍♂️

ETA; Got home, opened it up, fucking used and missing most of the attachments. Not sure if I want to ream his in negative feedback or live and learn, I do have the parts I can rob out of another I have, its just the principle.

I bought one of those this weekend as well. I didn't found out about the sale until later so I wasn't able to go the first day. They had some bigger 1720? Pelican rifle cases, but those sold out quick the first day.  I wonder what the foam cutouts were on those or were they empty.

I wasn't aware that they had been running the sale another day. I know they have regular sales over on the other side of the state though. Would be interesting to know what the other cases were.

Were you there around noon on Saturday?

A little fun at Talladega CMP.   Letting a buddy shoot.

I was gonna leave a negative review but since I checked out as a guest, I have to wait 5 days (new account) before I can post.  I got most of everything except one or two things, but I was under the impression that I was buying new. If I had known it was used and probably missing parts, I wouldn't have bought it.

They did this one Friday and Saturday. I was there on Saturday around 2:30-3pm on my way to work. They were in the same spot about a month ago. I went to that one as well, but all I saw was overpriced beat to hell big huge Pelican/Hardigg cases. I was looking for Pelican 15## or 16## cases and they didn’t have any. Both times I went on the second day so there might have been better selection early on the first day.

So I was out on the motorcycle this weekend up in Santa Fe, pretending like I know how to handle a 650+lb BMW on single tracks and what does my sorry ass come home to this afternoon?





The parts got finished at the anodizer over the weekend and I got the call to come pick them up as I was rolling back in to Dallas. It'll take me a good day or three to get the guides sorted, packed and stuffed in the mailing envelopes so I can make one big (heavy) trip to the post office, but we're finally at the finish line. And if I figured out the bulk shipping system correctly, everyone should be receiving a tracking email once the packages go out. Last thing, as a way of saying thank you for all your patience I had a little something extra made up that I'll be stuffing in with everyone's order so keep an eye out for it!

*excitement intensifies*

Noice!

I asked for a refund, so I will see if he replies or ignores me, either way I’m leaving negative feedback, I figure he has today to respond. Yea mine was used, the nylon brush is black and damn near worn out. I think all but two pieces are missing. I am beyond pissed at this. This has to be the worst of the lot he was selling. You could even smell it had been used before I unzipped it.

I would be pissed too. I kind of feel bad for posting it now, since it looks like I was one of the few that actually got what was pictured.  I'd definitely be opening a claim if mine showed up like that, especially since there was another much cheaper listing for what you guys wound up getting.

I wouldn’t feel bad for it, you had no indication it was a bad seller at the time. The ones that got bad product need to leave feedback accordingly. I sent a message the night I got mine and it’s been two business days and still no return message so he probably knew he was selling used and didn’t care.   At this point I’m glad I got two.... Two is one, one is none and all .

I’m happy like a little school girl!

I ordered one as well. It showed up yesterday. Brushes worn out, bag discolored with a big water/oil mark. I requested refund as I bought it because it was "new."

Anyone know if any of those Armalite OAR uppers are still for sale/available?  There was a gentleman that was selling some recently and I can't find the post.

Not sure if he has anymore but it was Eric Sydow in IG @esydow13  who had them. I got one and it looks great.

I got this reply this am, no refund yet though,
Attached File

Thank you!  I'll reach out and see.  Fingers crossed!

Mine came used with some extra bits hiding in the pocket, but mostly there; not new, but I can work with it.

If yours came with a OG bore guide or a Wilcox Dr mount I’m gonna be so mad....

Yea, no kidding, mines not even workable, and I still ha r not gotten my refund!

Darn!  Literally 2 hours after I posted this one popped up on the EE and was gone immediately.  I did reach out to the guy on IG and he's out but said he may have some more soon.

They look fantastic, another piece of the puzzle.

Eurooptic has NXS 2.5-10x24's in stock.

I don't see them. Gone?

Sold out.

Subscribe to in stock notifications. I guess it went rather quick. Email sent to me at 7:18 MST.

https://www.eurooptic.com//nightforce-nxs-25-10x24-zerostop-25-moa-moar-nvd-ptl-c462.aspx?

This ^^^ is how I got both of my x24’s.

Anyone got a bead on a correct Mod 0 FSB with flats?  My barrel over at CLE is about to be spun and I thought i would have one by now.  Was hoping to get it to them and get everything done in one fail swoop.  No worries if not, i'll find one eventually.

Update: late Mod 0.

I’m sure some of you know and it’s not my listing but a ARMS #38 Peq 2-3 rail for gen three is on GB.
As far as the front sight I haven’t seen one in a minute.

So....I got one of the NXS 2.5-10x24s from EuroOptic....under rather weird circumstances....we'll see if it actually ships.  Will disclose details if I actually receive it.

What gen mod 0?

Yes sir.

Do you have a link to it?  Curious what it's going/went for but I'm not seeing it.

I'm asking which generation of the mod 0.  The FSGB varies on whether you're talking early mod 0 or later gen 3 mod 0.
I have an extra set screw FSGB but it's a PRI repro of the early mod 0 one and also has the thumb screw sight tower.  Not sure if that's the kind you're looking for or if you're looking for a later mod 0 where the set screw base was more rounded on the legs and the sight tower did away with the thumb screw adjustment.  

item/898988889

My bad man, I super skimmed your message during my meetings this morning.  Yeah, it was late Mod 0.  Updated original thread with that detail because I was a big dummy.

LOL, all good!  Unfortunately I don't have an extra one of the correct late mod 0 ones but will IM you if I come across one.  Good luck!