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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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Yes, on the M38 rifle.  The probable reason for Leupold retaining the TS30A2 identifier, despite being a different scope.

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When did the crossover from mildot to tmr happen?
When did the 3-9 become the 2.5-8?

Went out and zeroed my mod 1 w/ the 3-9 today.  Not a single regret ditching the big x50.

I think the last year of the 3-9 Mk4 was 2004.  Was a relatively short lived scope.  Mildot to TMR transition really didn't occur with Mk12s as far as I know. The Marines went with the TMR and M2s turrets for their Mod 1s. Army was Mildot and M3s all the way through the Mk12 program across the TS30 2.5-8, TS30A2 & commercial Mk4 3-9s and Vari-X III Tactical 3.5-10 scopes.

Now that I have the proper glass, I really want the proper rings.  Still after all these years it's my favorite rifle in the safe.

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Ya, I’ve reached out multiple ways so we will see if I get a reply. I’m not wanting to buy four AEM5’s right now, but I also have a hard time not having a dedicated suppressor on everything I own.

Is that the recent Larue Leupold offering?

Nope. Like hunterex said, that scope hasn't been made in 16 years

The 3-9 became the 2.5-8 in 2006, the earlier mk4's were 2003 in their brochure in 2004. In 2006 the tmr became available. They were still buying mildot models even after 2006.

I suppose I didnt put that in the right context, the early mk12 optics the leupold ts30 and ts30a2  have nothing in common with the 112633. Why leupold named the 112633,  the ts30a2 is probably just marketing.

This has always confused me.  Other than the illumination housing, how are they different?

The issued TS30A2 with the Mk12s is the same scope as your commercial Mk4 but with TS30A2 written on the side basically.

So Mildot, M3s, 3-9, 62GR turret, blended illumination housing.

The later TS30A2 (112633) is TMR, M2s, 2.5-8, 77GR turret, slabside illumination housing. Alignment lines and a battery cap tether added.

Issued TS30...

Same scope off the rifle...

J = 2001

What's the most likely paint/color in the downrange photo?

Why?

I just picked up a 2.5-8 mk4 for a song and I'm not sure what to do with it. I had one before I had my mod 1 and tried it one my Holland. Didn't like it that much and got rid of it right away.

Guess I need to give it another chance now that I have a good load worked up for them and have switched from paper punching to steel smacking.

Does anyone have a formal breakdown of the year-code for Leupolds?

Not being snarky, google Leupold Scope Year Codes and it's under the Leupold FAQ on their website.

ok to shed a little more light on the optic discussion.

I have data on a true ts-30 a2 3-9x, a commercial round body 3-9x, and a modern 112633 2.5-8x ( all pictures are in that order)

The ts-30 a2 and the commercial round body 3-9 both have mil dots while the 112633 has TMR

body to body there is almost no difference between the ts30-a2 and the commercial version. Aside from the ts-30 a2 marking, the ONLY difference externally is on the objective lens end there is no identification engraving in the ring on the ts-30 a2. the commercial is marked leupold mark 4mm 3-9x36 mr/t. The 112633 is marked, in white text the exact same, however i have seen these marked with engraving only and no white fill on other 112633. Also as pointed out earlier the 112633 has a slab body illumination housing, a tethered cap ( tether to body removed from this example). As well as laser lines for scope mounting.


On the body itself there are obvious  branding marking differences, and serial number location. I will note here on the commercial 3-9 the " leupold" is much lower than on the ts-30 a2 if you ever notice a ts-30 a2 mark that is trending very low it is possibly a commercial version that was later laser on as a fake. Also not the hex bolts used to tighten the elevation and windage caps, on the original OG stuff they are always black. on anything  newer they are silver. Also you can see the difference in the BDC engravings on the 77gr turret  used on the 112633, the text is larger and layout is different.


Finally the biggest difference of all is the Ocular lens. this is true for all 3-9 VS 2.5-8 & all 3-10 mk12 variants including Vari-x III. as you can see in this picture of the ts-30 a2 on the left and the 112633 on the right. The ocular lens is smaller on the 3-9 which does produce a smaller image.

CAR stock is best stock. Looks great on the mod 1.

I think the 2.5-8x and 3-9x have the same actual magnification. If I remember correctly the 3.5-10x is slightly less than 10x on top in reality too. I’ve had at least 1 example of each and all things considered the 2.5-8x TMR is the best fit IMO.

Nice writeup

Great stuff.  Makes you wonder if the changes over time were based on feedback and repairs from Crane.  The battery cap, for example, is missing on a lot of the in field photos, so adding the tether makes sense.  The slab illum housing could've addressed durability issues there and the lens change might've improved field of view as issued buttstocks and use of body armor dictated over time.

The DoD photo of a Marine with a 112633 scope on what appears to be a Mk12 rifle in July 2013 considered a one off “in the wild”? Or can a 112633 scope be considered correct for a late USMC Mk12?

Got a link?

Here's a 112633 in the wild.  Exif data on the image shows Nov 2014.

That should be the same one he's referencing. It's been tagged as July 29th, 2013.

Yes, that is the photo I was referencing.  Another DoD photo of the Lance Corporal Wilson in Afghanistan on the same date.
https://www.defense.gov/observe/photo-gallery/igphoto/2001119841/

That scope may have been a replacement or even T&E as the Corps was in the process of killing the Mk12 as it was taken. Time wise it falls after Leupold made the changes and added the 112633 to the actual Mil and LE catalogs and added it to the NSN for the Mk12 optic.

The stuff I've heard from the guys that actually pulled the Mk12s apart and sent the lowers off to captain crunch in the Marines lines up that this would have been while all that was going on. 2012 and onwards is when that was happening, someone in the FB group saw the lowers with his own eyes around then. Like the Army SF and Ranger side there may have been the odd one seen collecting dust in the armory in the following years but effectively the Mod 1 was pulled out from line infantry units around then and unlike the SF, that means they aren't coming out anymore because someone on the ODA still thought it was cool.

If you want to do this properly then I suppose anyone with a 112633 would have to set up their Mod 1 as a Marine rifle, no paint, yet their overpriced Leupold down the driveway, and then say you specifically built a 2012/2013 last deployment gun.

Form 3 from Capitol Armory for my AEM5 finally got approved. Finally going to start the long Form 4 process

Nice! May your wait be quick and short!

One of the Plt Sgts in my old unit painted their Mk12s. It was right towards the ends of the Mk12 era

Attached File

Oh good.  Maybe mine will get approved soon. Have a tax stamp waiting on my Silencer Shop account for it.

Just purchased my tax stamp this morning from Silencer Shop. Hopefully can start the process next week for it.

I thought issued optics were illuminated?

TS30 was issued with early Mod 1s. It's a non-illuminated 2.5-8 with a fairly unique profile.   Has the Leupold European type turret housing and classic focus ocular housing versus the fast focus of the non-illuminated MR/Ts.

Thanks for the info,  much appreciated.

Thanks to everyone for their replies and information.

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Finally found some #22 mediums and mounted my scope today. I noticed some play in one of the ring bases, is this normal for these rings? This is my first set of ARMS rings.

Mine was the same way, absolute junk. I "fixed" mine by filling the dovetail with devcon. ARMS said they would fix them but I'll personally never trust them again.

I ended up buying some Badger rings like I should have done in the first place!

And no that's not normal!

Thanks, that’s what I was afraid of. It took so long to find some new in stock that I’m hesitant to send them in to ARMS. When you used devcon, did you just smear it in the dovetail gap an wipe off the excess? Has it held up pretty well to the recoil?

I disassembled them and coated the dovetail,  you can't tell I did it. As far as holding up,  I have no idea i haven't put them back on but devcon is some tough stuff. I was more worried about the rings being out of alignment.  I guess they'll just sit in a drawer because I wouldn't feel right about selling them to someone.

Gotcha, thanks again!

If anyone is looking for an AEM5 in Houston, Collector’s Firearms had 2 in the case Saturday. I think one was $609 and one was $669. No idea on why the apparent pricing difference... The tags were a bit obscured and the place was pretty busy, so I didn’t ask.

Edit: both gone now.

I need to find a new house to move into- most of my stuff is in storage currently. But once I do, I’ll post some pics.

One on the right is correct?

That's the one.

@SaturationTech  Thank you for the lead!  For anyone else looking Collector’s firearms now has one AEM5 in stock as of 19:17 EST  its a smooth body   the other one vaporized when i called

No problem. If I hadn’t just picked one up from Capitol Armory, I’d have seen if I coulda gotten it transferred to my dealer...

Yeah I was going to get in line with them at Capitol armory in the morning but they said it would be in the next 30 days. Hopefully this will lessen that wait by a week or two.   One part less to source I guess.