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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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How about some PRS Gas Gun Club Match Mk12 action

Far out, how'd you do?

That's badass. I want to do a PRS match with my Mk12. How'd you fare against the bigger caliber rifles?

I'd like to do one too but there's not a ton of info (like cost) on the site.  I don't want to waste my time and theirs filling out their survey (and giving a known personal-data-collector-and-reseller like constant contact a bunch of info THEY don't need) just to find out it's way more than I can put down right now for a "just for fun" kinda experience...

Next year I suppose.  

Shipping was $24.25.

anybody going to clue the rest of us in since apparently they sold anyway?

Pair of pelican cases off of ebay

im not salty....i need a mod 0 foam layout...just realized. I guess im gonna cut em out new then. 

gotcha, thanks.

already got mine, so nothing to worry about from me as far as sniping auctions goes.  

K_weez, great pictures, there was supposed to be two national level PRS has gun matches here in WA, but one got cancelled, I will have to wait till August since I will be gone for the only other one close to me is in Idaho.  But I may end just shooting it in some of the bolt gun matches.
ArmedFerret, you don't have to be an actual member of the PRS to shoot any of the matches, you can always just look on the website and  see if any of the matches are close to you. It's a $100 for PRS membership, but the matches are all run indepently, it really depends if it's a local or national level match with regards to match entry fee. Our local matches usually run about $50, a two day PRS bolt/gas gun match about $200.

Must have auto-calculated based on location.  I was seeing $40 - I actually tried to snipe the good one @ $300 but got an eBay error page.  Whoever ended up winning the good one can thank eBay for it

As much as I wanted to hold out for a Mod 0 foam arrangement, the foam quality was good enough on this one that I was willing to spend the ~$100 premium to just be done with the daily eBay searches.

The foam condition was the same on both, one just had an extra cut out in the lid for some additional accessory that the end user deemed necessary to have its own spot in the case. To me that cutout looked like it was for the Harris Bipod but who knows. Either way both were definitely heavily used, regardless I am happy with my purchase and glad that I don't have to look for one any longer.

Thanks man.  Sadly the only one remotely close to me is in WV which is a goodly haul and would easily become 4 days of leave rather than just a weekend trip that didn't result in losing leave.  Maybe next year they'll have one at Bridgeville (haha yeah right, those guys are pricks)

As of today all manuals are mailed that I've recieved payment for. Please let me know if I made any mistakes. Wrong manual or labels or anything. If you wanted labels and I accidentally left yours out let me know I'll send them. I think I got them all though. Still getting a count on the other items. Should have an ETA on logs in a couple days. I'm working with the printer on the Ballistic cards. I will post some ideas later today to see what everyone thinks.

Movistar's upper is in the ee.....we need to keep that one in the family. Sorry it's gotta go man....I would take it from you if I wasn't in the middle of a block 2 build.

Thanks for doing this, looking forward to seeing this manual.

Good luck everyone else...

Gen 1 ACE SOCOM

...I ducked out once it hit $800.

Wow!

That's insane. Kind of seems based upon the description that the seller had no idea what he had.

Haha....I was going to watch it towards the end but I guess I don't have to worry about it now. I guess there's a lot of people getting into clones lately that have extremely deep pockets

I knew that he was the one...I watch his parts auctions pretty closely.

Crazy stuff, at some point it is just going to be easier (and cheaper) to have someone make/modify these types of parts.

Right!? I hate to say it but I think we may be approaching that point. Who's the best machinist in the thread? I say we establish that then we all pitch in to get the machinery up and tuning and we just start making our own stuff....haha....I'm only half joking

Honestly this hobby for some guys is really nothing as far as money goes (not that I am one of those guys lol) If you want to see what real money (IMO) is (or get scared) start looking at pricing on Cars and Parts for early Ford or Chrysler Hemi / Wedge Super Stock parts...or for just a basic Cobra Jet or 440 Six-Pack car...some of the hoods go for more than one of the original SF Group Mod0 uppers just sold for (and there is like what a dozen of those floating around?). Its the same for offshore boats, large sailboats, Cup car racing, Airplanes etc...In the big picture, dropping 3K to 5K is nothing for a lot of these dudes...plus they do not want to 'hunt' it...they see it..they buy it.

I have been saying that for awhile now...This industry is getting to be in the same boat as automotive restoration...when all the good original parts dry up your only option is aftermarket / reproduction (and for the most part those parts are not as nice)

Oh when it comes to hobbies there is no arguing this is probably one of the cheaper(ish) of them....not to say it cheap bc it isn't....lol. It's just crazy how insane prices have been getting over the past few months. When the well dries up...and it will eventually....there's no telling what prices will shoot to.

Having recently dropped $8k on a gear-set for a rally car, I can relate.  Guns are an expensive hobby, but there's always something worse.  AR-15's aren't even that bad compared to other guns - when I sold my M14/M1A and some spare parts, it sold for ~$10k and I was taking a significant loss when smith labor was factored in.

I really wanted to cap out at $600 for that Mod H stock, but I saw 'screw it' and bid $800 just so I wouldn't have to come back for a week...  my bid lasted 5 minutes.  I backed off on my Mod 0 and started a Mod H build due to the rarity and rising cost of a set-screw front sight... so much for that cost-saving idea, I guess.

I never thought that I would see these prices.  800 for a stock!  At these prices I'm half tempted to sell mine and throw some fingers to the air.  I've got other expensive gun hobbies!

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Got a nice little toy in the mail from HCS today...

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I bought one in97 when they were one of a few.  Don't let it fall on your foot.  Don't ask me how I know.

Dan

That's great man! Congrats!

Cool to see he's installing long collars on them now too.

Complete upper from HCS? Congrats!!!

I got my barrel and brake/collar from him today, can't wait for the rest of my parts to show.

work of art

Yep I am too. I ordered a collar/brake from him for my recce and it was the SPR collar so I was hopeful he would use that on this rifle.

Got the PEQ-2A mounted. Leupold MR/T is off getting M5 dials put on...yes, you read that right. It can be done now.

Now, someone sell me some NLS #22H's for this beauty!

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Seeing this makes me wanna keep my mod1 upper now

i shortened a gen 1 rifle socom to a carbine. not too hard of a job. someone in here is rocking it now :). you just gotta know where and how to thread and put dat angle in there ;).


my socom was $120....but $800........man id almost sell mine for that but it took me a year to find the right price so nahhhhhh haha. 

Congrats!  Mines taking a licking and keeps on ticking, he makes a solid upper

One word for you:

Given that it was a match geared towards larger caliber guns (1000yrd+ targets, a 500yrd spinner/popper combo) it did amazing. I came in middle of the pack. Beating out 6mm/6.5mm bolt guns felt good

Best stage for me was reaching out to 1014yrds off a roof pitch and hitting a man sized IPSC target repeatedly. This gun is no joke with 77gr SMK's.



Thanks buddy.

I was planning on doing the WA PRS GG match shooting tac light with my mk12. Do you know which match got cancelled, the bolt gun or the gas gun? I signed up for the Idaho MGM match as well. A buddy and I will be driving out and plan on shooting tac light there. I'm trying to find a partner to go to the Colorado match because I really want to go just not by myself. I'm really excited for this series. I shot my bolt gun 2 years ago. Hopefully we could meet up at one of these matches.

Agree, seems like he just thought he was selling a run of the mill stock for $80 or so... bet he is happy :).

Is the long collar correct for Mod 1?

Well that's it, stupidest fucking thing I'll see all day. Its a stock ffs. How do you tell a "Gen 1" ace from the others again? I seem to remember a thread page on it.

Yes, and for mod 0 and mod H abs all issued rifles using an ops

Is there a Texas mk12 shoot? Im in El Paso but would make the trip to meet up with some arfcomers to shoot the shyt.

This comes up quite often.  Seems like best of the west in gatesville is a popular request.

If this ever comes up would someone be kind enough to shoot me a IM.  I need a road trip to get away from work for a while.

Page 1 of the Holland thread has pictures showing the difference; I'm a visual person

10/4, thanks. I'm going to keep an eye out for those, once I find one, let's start the bidding at

Is that for real???? 801.00 ????? Will people just bid like that then not pay just to be an ass? Does that happen on gunbroker? What did I miss about that? I ended up with 3 gen 1 ace stocks while I was hunting. One long and two short ones. I will dump all 3 for that kind of money if someone will really pay that. Holy shit that is crazy. I saw an mk18 RIS II in the EE for 750.00. Fuck retirement accounts I've got clone parts. This shit just blows me away. I'm starting to wonder what the BCM built SAM-R upper I bought for 1300.00 would bring. ...... honestly I probably would not sell any of my parts but the 800 for a gen 1 ace stock is really tempting. I know people catch shit for that here but DAM!!! I could have a good start on an mk11 by selling a few things.

Now to serious shit. Which of these 3 should we use as the ballistics card? First one is from the manual and I thought about having the moving target leads,mil-scale range and everything on page D-2 printed on the back. The second is the one from ballisticard. The third is the one someone posted a link to a page or two ago. I'm thinking 4x6 laminated cards. I held a 4x6 and a 8x6 card and 4x6 seemed good but what do y'all think? Sorry for the shitty screen shots but that's all I've got.
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I like the first picture. It would look extremely legit laminated