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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

Obj 13.  However, you have soften it in warm water to mash it on.  I tried 14 but it was slightly loose.

Eye 19 is perfect.

10-4 that be awesome

For anyone who owns an issued Pelican case for their MK12, were they only black or did they also issue tan?

No idea but mine and any others I've seen pictured have been black.

Here’s one that I presume is real.  I bought it used so one never knows.  But these are some dimensions if need to ensure the bipod stud is identical.  Pictured next to a newer mount:

That is exactly how I am going to make mine; the new ones are MIM.  My stud dimensions are almost identical, 0.730" x 0.305 on the flats with a DIA of 0.365.

Just saw some A.R.M.S high rings on fleabay with a $450 buy it now. Eeek! I wish I bought some 10 years ago.

If legit NLS Rings that’d be the going rate bro

Forgive me but I tend to forget things sometimes. I assume NLS stands for No Lever Stop. The rings in the picture do indeed have the lever stop.

You are correct. Mounts Plus has (or had) 22Hs for $150. I just got a set in today.

Yeah, it means no lever stop. A lot of people who aren't into cloning will see NLS #22s go for $400+ and think their new production ones with the lever stops are worth the same because they don't know the difference

Does anyone have a line on a #40L?? I missed one on the EE a couple weeks ago.  I have a minty wingless #40L if anyone wants to trade like for like.  

The Asian airsoft copy swivel/bipod studs fit in the KAC brackets.
https://www.ebay.com/itm/196140486045

Brownells has some in stock as well

Rock River Arms has the #40 A2 and #40L on their site

Damn Ebay and GunBroker on the stupid!!

solid copy.  Thank you!

THANKS, I ordered one this morning!

Yep, I almost sold someone a brand new set of rings here for $120 that I listed on the EE. He asked if they had the stops, I said no...then realized the value of the NLS rings and that forced me into building my MK12. Well that and me having a number of other parts on hand.

I asked for pics instead of saying I'd take them.

Its more than just getting them on.  Even after you do, they don't stay well (hence alot of pics of duct tape).  The other issue is with mashing them on, the small rim that is on the body can get misshapen or stretched and is no longer able to allow the cap itself to snap into place.  

I called Leupold direct and they sent me out a pair of the original covers if you don't have them.  They fit like a glove.

Haha yep that's what did you in, ended up doing a little research, saw what they went for and said heck I'll build one myself.


Though in reality, that forced me into a Mk12 clone which was not the best financial decision in the world for me

I never realized the sling swivel/bipod studs were marked KAC. I looked at a loose bipod mount and sure enough there were the letters KAC in the recess of the stud.

I just prefer to cheat for half the cost

^^^ he does good work!

Were Mark 4 3-9x36 MR/T illuminated M1 optics ever seen in use. I have a L prefix so 2003 production year scope in route and was wondering if they were used on any mk12's or any other clones.
PFA:

My podlock broke. Darn.

Bought this thing 15 plus years ago. Has the design changed at all? I just ordered a replacement from Brownells and thought I don't want the clone gods frowning upon me because some minute change.

Are there any more contemporary pics floating around of Mk12's in service?  I know we have a few posted some pages back.  Was wondering if anymore are out there.  I can't seem to find any.

Possibly, depending on what version you have. What broke on yours -- the lever? If you still have the parts it should be fixable...

First version used a slotted screw. This would be around 1999-2000, mostly seen on M24s. Don't have one of those for reference.

Later changed to a hex screw. Not sure exactly when, likely by early-2000s. This one is a 2006.



Then changed to a tamper-resistant hex screw in 2007 (left). Right lever is from an EABCO S-Lever.



Old style/gen 1 (below) is a two-piece design -- separate lever and spacer. New design/gen 2 (post-2009) is a one-piece arrangement with a bent lever embossed with "KMW". Don't have one of those either but it should be the stock image on the KMW site.



IMO a gen 1 pod loc is worth fixing. Replacement levers are available.

Here's my Mk12 Mod 1 completely finished! I have a PEQ-2 for it in the safe, it just looks better without it on the rifle. I also have an original Mod 1 case with accessories, but those aren't important, the rifle is what matters. This is a beautiful rifle, and I'm extremely proud of this build!




Here's the parts list, a few of the parts are extremely rare! Some of the rare parts, like the PRI patent pending charging handle, probably weren't used on the Mod 1 rifles, but I wanted to build a Mod 1 with the most amazing parts that I could possibly find! How many rare parts can you spot?

- Early PRI welded latch and patent pending engraved charging handle
- Early Ergo grip with the stylized "E" logo
- Early USA made Uncle Mike's sling loop
- KAC Vero Beach sling stud mount
- KAC Vero Beach bipod mount
- KAC Vero Beach PEQ-2 mount
- KAC 200-600m rear sight
- KAC prototype 99051 front sight with the flat front and no laser engraving (SAM-R issued)
- KAC Vero Beach M4 Match FF RAS handguard
- ARMS 22H no lever stop scope rings
- Original surplus USMC used Leupold 3-9x scope
- Original surplus Mk12 Mod 0/1 take-off barrel
- Original NOS condition surplus Mk12 Mod 1 JRC marked gas block
- Original NOS condition surplus Harris bipod (slip of inspection paper dated 2006 was in the bag with the bipod)
- NOS condition Colt AF upper receiver with BCG (take-off from a 1999 barrel dated complete Colt upper)
- Allen Engineering AEM5 silencer











What do you guys think? How'd I do with this build? I'll have to post my Mk12 Mod 0 later, that build turned out great too!

All that purple.

I think I'm the only person you don't tell to paint his rifle, lol

Does anyone have an old gen 1 Pod-Loc available? That's one of the few pieces that I'm missing, I'd appreciate any help with finding one or 2 of them

I mean...paint wouldn't be bad, but purple needs to see the light of day. Plus, 99% of your stuff is museum-level stuff not Larp-level like the rest of us peons.

.  Prob doesn't get much better than this.  Congrats!

Had a few nights days this weekend and got the Mod 0 and H out.  Hitting 600 silhouettes is just too easy. Using some of the PSA 77gr SMK rounds.

Found some Diemaco AH uppers the other day, guess I’m building a MK12 now… The clone gods don’t want me to stop because they keep giving me great deals. Chopping one for a MK18, and keeping one for a M4.

Picked this pvs-22 up for my xm-3 build but damn if it doesn’t fit right at home on the mod1

@metalsaber got a link for these? I'm not seeing them.

https://palmettostatearmory.com/aac-5-56-nato-77-grain-sierra-matchking-hpbt-20rd-box.html

Be still my heart... Wow that's gorgeous. I'm afraid to ask how long it took to track down all those Vero Beach parts

Ah, thanks. I was looking for PSA-branded.

@Shlouf

That bitch is sexy!!  Did you cerakote it or is that just a nicely laid spray job?  Anxiously awaiting my scopes arrival too..................

The PVS-22 looks awesome on your rifle! I grabbed my PVS-22 from my original USMC XM3 kit that I bought from the CMP years ago (it's 1 of the 4 XM3's that my Scout Sniper Platoon had in Fallujah, Iraq in 2008, and was issued to my friend!). Here's what the PVS-22 and PEQ-2 look like on my Mk12 Mod 1. Gotta say, it looks awesome!






I also wanted to see what the PVS-22 looked like on my Mk12 Mod 0. Looks good, but as you can see in the photos, the PVS-22 doesn't line up very well with the Leupold TS-30A2 scope in the medium height Arms rings.

Here's my Mk12 Mod 0, it's also built to crazy perfect specs like my Mod 1! This rifle has an original military used take-off barrel and it has the correct Mod 0 folding sight gas block (FSGB)! I've seen multiple crazy rare SPR FSGB's over the years, but this Mod 0 FSGB is the only legit actual Mod 0 FSGB I've ever seen. The Mod 0 FSGB has 4 set screws holding it to the original barrel, not the 2 long bolts like some of the older FSGB's had. The Mod 0 handguard is an original surplus Mod 0 piece, it was made around 2003 and has the correct size/location vent holes. The original Mod 0 handguard is extremely rare! You guys should recognize the original Leupold TS-30A2 scope, Arms 22M no lever stop rings and the Arms Tactical Ring Cap (TRC). The Arms #38 Swan Sleeve is the PEQ-2 type, which is correct for the military Mod 0's as well.




I also have a vintage Docter Optic red dot sight in a protective winged mount. The previous photos are the Mod 0 without the red dot, the 2 photos below have the red dot attached. Which way do you guys like better?




The GM Hydramatic receiver was cistom made for me, and the serial number on it actually matches the original government issued Mk12 Mod 0 serial number that's on my original Mod 0 case! The serial number range on the original case actually matches up to the GM Hydramatic receivers (not Colt or H&R or any other company), so I decided to do a reproduction GM Hydramatic receiver for my build using this serial number! This is probably a one-off pair, I've never seen another receiver with a serial number matching an original Mk12 case!





I actually have this Mod 0 available for sale (minus the silencer), a friend is currently thinking about buying it from me. It's expensive, but it's probably the best clone Mk12 Mod 0 ever assembled! It's truly a labor of love, a ton of time/money/effort when into this build, and I hope all that effort can be seen in these photos!

Very nice rigs.

Mod 0 lines up a hell of a lot better than the XM-3 does though

Here's both of my builds, which one do you guys prefer? I love both of these rifles, they turned out perfect and they look amazing together! It's difficult to say if I like one better than the other. What do you guys think about these clone builds?

I like cheese graters and purple. Especially purple cheese graters.

While I ended up with a KAC rail from the last batch, I think my Mod 0 and Mod H will receive more range time.

The PRI tube is just so iconic…

Hell yeah!