* * * * * * * * * *

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:

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Attached File

FUCKING RANGE TIME

Torqued the barrel last night. Finally gonna get to shoot this beeitch.

11.2 pounds unloaded with the BA barrel.

-anfratz, you need a long bottom rail on that bad boy!











 

Whats the deal on this one? What type of rings is this one using? Was this one even used in the field?

Don't feel like you are the only one this has happened to.   Mine wasn't quite that long but after 6 months I called atf to talk to my examiner personally.  He looked back through his paperwork and saw that he approved it and "mailed it out."   This was over 30 days after approval.  I did the certified copy thing from him too and then a couple months later my dealer received the actual form 4 in the mail.  He called the examiner back only to find out he retired and several form 4's were also "found" in his desk and promptly mailed.  So my dealer had 2 of these back to back!   What a crock....

 
Those are NightForce lowrider rings. I believe this Mod1 was used in an NSW weapons display for civilians to peruse at a public event of some kind. I'm assuming it wasn't just for show at some point, though I can't say for certain.

Just listed my NF rings in the ee if anyone was looking for a "will work and be ok on mk12" rings

Nightforce lows.  I would bet money that scope set up came off a Mk14 Mod 1 and was just thrown on the Mk12 for that display.




And here is the opposite:  a Mk14 Mod 1 with 2.5-10 x24 with ARMS 22H....most likely from a Mk12.

I hope that happens with mine. I would like to have the damned $200 stamp I paid for.

 
Says a lot about how scopes and parts travel around on different rifles, regardless if photos exist to prove it. It just makes sense.

Does anyone know if nightforce and arms top rings are interchangeable? As in the Wilcox mrds mount onto arms 22h rings etc (4 hole pattern)

(Hopefully no one leaned too far into that Mk12.  The fucking bipod is on backwards.)

Mod 1 build is being wrapped up shortly, although im having a hard time finding a Leupold at a decent price for it. Think i'm going to wait on the correct optic and get a viable one for now. I mean that intercooler for my supercharged mustang is calling my name now, time for 500whp . Any suggestions for a relatively cheap scope? Looked at the Leupold mark AR scopes and ive seen a few Vortex viper pst 2.5-10x32 ffps at good prices recently. What do you guys think for now? (it'll get a proper mk4 or nightforce someday )

Took 23 high schoolers shooting this Saturday. Many of them had never shot a gun before.

Taught them about safety, weapons manipulation, etc... needless to say, started them all on the Mk 12 for the first round they've ever fired in their life.

I was a proud papa.

Mk 12 in here somewhere

Didn't group as well as I would have expected....but it was windy out. Averaged around 2,780 FPS.
" />

Want to make sure that this is the correct scope before I make a purchase. Doesn't specifically mention it's a TS-30-A2 but does state it has the TS-30-A2 markings and the correct turret? Help is appreciated.

http://swfa.com/Leupold-25-8x36-Mark-4-MRT-30mm-Riflescope-P52988.aspx

How'd it group?

 

That 2.5-8 looks "correct". There's also the 3.5-10 M3 and the 3-9 M3 that has shorter eye relief (you can mount it on an AR w/o using an extended base). When it comes to leupolds I usually shop the used market because they are a lot cheaper and the warranty is lifetime.

1moa+

There's one of these for sale in the EE right now.

MK262 has never grouped for me or anyone else, I've talked to. It shines down range and terminally more than accurately. What I mean is it'll shoot that 1 MOA group out to 600+. I'm intrigued by the new 5.56 TMK and the new Barnes 85 grain'ers. On paper the TMK goes to 1k.

At any rate, try some Nosler 77 grain Custom Comp for small groups. I've had sucsess with these and the nosler 69 grains.

Try telling Naval Weapons Station Crane that MK262 doesn't group.  I've shoot several good groups with it from 100 yards out to 600 yards including several cleans at 200 yards with it.

Bh gives me .75moa. At distance its disgustingly good.

My special sauce gets me .75-1moa at 100 and matches at distance.


The green tipped sierra TMK vs otm 77gr was exactly the same @100 for me. I shot both on same day from my old recce. .75" @100


My go to load is 24gr of xbr8208 on the 77gr otms. Never pusjed for velocity or tightness...yet. Once i reload i will.


Ramblings from a cloaner to ya'll :)

'Me or anyone else I've talked to' didn't include Crane, so I'm glad you've got that covered.

.75 is about what I was getting, and like you said it's down range where it shines.

Just got back from the range with the Mod H, and I'm very pleased. I put 60 rounds of M193 through it to get a copper base, and then switched to the CBC 77gr OTM. I haven't been to the range since (shit....) early December? So I was rusty. My groups averaged 0.75 MOA, but then a single round with good form to confirm on a shoot-and-see bullseye would be dead center, and repeatable about three times!

Barrel is a 16" Ballistic Advantage 1:8, the medium/governmentish profile version.

Conditions:

48.5 degrees F
4230 feet ASL
4764 Density Altitude
10 mph avg crosswind

Scope has M2 turrets, so here's the DOPE that worked in MOA (with suppressor attached):

Yards / Drop

100: 0.0
200: 1.0
300: 3.5
400: 6.0
500: 10.0
600: 14.5
700: 19.5

Applied Ballistics calibrated muzzle velocity to 2775.32 fps (with the can)

For reference, my 18" Doulags 1:7 with the same CBC 77gr OTM calibrates an MV of 2886.39 fps

Those numbers sound about right I think?

Going from M1 to M2 turrets has it's tricky points. We moved the steel to random yardages (337, 455, etc), and a few times I had to kind of guess the best call as I learn the rifle. Such calls would have been easier with 1/4 MOA adjustments.

I will say, though, I'm impressed with this barrel at distance. At 300 yards, this thing was stacking them the equivalent of 0.65 to 0.75 MOA. Not too shabby for a $153 barrel!


Also, here's our hostage setup, target is the white steel inside the "bus": (-1 point for hitting a human, -2 for hitting the dag) Sick shit, eh?

That's awesome haha!

I got about the same results from 77g TMKs and SMKs.  I used the same load, same brass batch, etc.  I had the same dope at 600 last week.  I didn't group on paper because the wind was shifting/fishtailing at upwards of 20mph, but I was able to make consistent hits on 8" steel plates.  

So you were pleased with the Ballistic Advantage barrel?  I got the 18" SPR profile for my mk12 project, can't wait to see how she shoots.

Hopefully continuing my build this week. Need to pick up some roll pins for the upper (didn't lose any springs,but had an awful time without a roll pin starter. So going to get that as well.

Aero Upper
18" Ballistic Advantage SPR barrel
PRI forearm and FSB/ gas block


Is finally going to start looking like a rifle.

I only put probably 160 or 180 rounds through it today, but with Mk262 Mod1, it shoots like a Mk12! I'm a happy camper.

They have a really nice muzzle on them, too, I noticed when assembling. The crown is significantly recessed, which is a nice feature I've only seen on these barrels. I should have grabbed a photo to post, but it's sweet. They did a great job with these, not to mention the attractive price point.

I was skeptical at first (IE: You get what you pay for), but through that I've never seen a poor review of them on this thread now that I recall.

Happy to hear for both of us!

The price point was what sold me on them. The Douglas wasn't in my price range, and this was. Heard good things so bit the bullet. Can't wait to get it together. My first build, hopefully more accurate than I am.

No classier way to do it.



 

Didn't group as well as I would have expected....but it was windy out. Averaged around 2,780 FPS.
http://<a href=http://i724.photobucket.com/albums/ww245/Davey_Sickboy/20160319_114648-01_zpsz0vaollc.jpeg</a>" />How'd it group?  
1moa+

MK262 has never grouped for me or anyone elseI've talked to. It shines down range and terminally more than accurately. What I mean is it'll shoot that 1 MOA group out to 600+. I'm intrigued by the new 5.56 TMK and the new Barnes 85 grain'ers. On paper the TMK goes to 1k.

At any rate, try some Nosler 77 grain Custom Comp for small groups. I've had sucsess with these and the nosler 69 grains.

Try telling Naval Weapons Station Crane that MK262 doesn't group.  I've shoot several good groups with it from 100 yards out to 600 yards including several cleans at 200 yards with it.


'Me or anyone else I've talked to' didn't include Crane, so I'm glad you've got that covered.

Yea, well what I was saying was that for me, with my gun....it was just eh. I've waited years to run it through my mod1, and I really wasn't impressed. I know it's a fuck of a lot better than that 855 shit we've got, but my 77gr hand loaded Noslers group .5moa pretty consistently. But....I've learned over the years that my gun does not like cannelured bullets, so that could be it.

This post Needs to be stickied on the first page for a complete mod H expectantcy report. Good job sir. I agree with the dopes and all points.



Based off quick dopes on my M3 7.62 turret

Thanks for the confirmation (I assume that's PA elevation?)

I like the fact that the M2 turrets give you some level of tuning, but the nature of the turret seems to be geared towards speed shooting. That is, you have the complete capability of the weapon system in less than one revolution.

I do enjoy the M1 turrets for fine tuning (and reporting more accurate results to velocity calibration algorithms), but I feel like the M2 is geared to "knowing your basic DOPE and getting on target, then fast follow up shots", particularly with the TMR reticle. Combined with the weight and dimension of the Holland, it's a perfect union. I think this is going to be my favorite rifle!

Now, I can't imagine doing what I did today on M3 turrets. They obviously work, or they wouldn't be made, but dang! That's some minute of man stuff right there. Do you ever get frustrated with M3 turrets, or do you prefer them?

Edit: Re-reading my post, I'm finally realizing the point behind the Mk12, perhaps specifically the Mod 1 with the intended Mk4 2.5-8x36 M2. It's not a sniper rifle, it's a way to reach out and touch someone quickly.
I've been missing out on this revelation the whole time with M1 turrets, haha!

In love with M3 mil/moa.



Yes its all about that:






POP POP POP






"tango on the hill take his ass out!!!"






Mill target........dude takes up 4 mils......well 8 mils =200m, so hes about 400m out. Check turret......400 dope is above 10moa on the turret.



*click up to 10 to 10moa, PSHHHHEWWWW......tango down






And that us what the Mk12 is for ladies and gentlemen.




 

If there was ever a need for a "Like" button your post is it.



 

+87

Its actually 5 mills =400m..half the stadia...but you get it lol. I havent ranged humans in a bit so forgive my error.....a nut shot vs a torso vs a head....who's counting hahaah
 

But yes that is the essence of the Mk12 for me. And i believe its the best quick shot/quick followup weapons system in the 5.56 chambering

I bought a used "SPR" upper off a guy on here that has that barrel and it shoots pretty well, some of the groups have been surprisingly good. It's not overgassed and the crown and chamber are all done properly as well which is more than I can say for some other "cheap" barrels I've bought.

Mk262 stencil making

High Caliber Sale MK12Mod0 Upper good to go? Im a long time lurker and would like to plunge in the mk12 world. Any other suggestions for a complete build?

It's definitely good to go.  They make a Mod 1 clone about as close as it's possible to get.  I know they also made the rifles used, or at lease I'm told, for Lone Survivor.

Where are all the Colt parts?! I need to finish my Mod 1!

Damn, that's pretty.





Needs some paint though.



 

Oh, so that's what the company name Tango Down means!

*embarrassed*

I think it says mod1. I'm not home right now though

 
Doesn't matter. The only difference is the Mod number and the lot number.

It says mod 1. Just checked the 501st pics

 

LOL

What's the going rate on a set of non lever stop 22m arms rings?