MK12 MOD 0 SPR- .224 Valkyrie Build and Info

LRSHOOTER0311

Green Eyed Devil
Full Member
Minuteman
Feb 7, 2018
243
52
Hey guys,

So a quick backstory, I served in the Marines and was deployed during OEF 2010-2011, where we served as the initial boots on the ground during the "Battle of Marjah" (Operation Moshatark), in Southern Helmand, Afghanistan. Before I arrived, I was picked (volun-told) to go to the USMC DMR school where I was introduced to my true love, the MK12 Mod 1 DMR rifle (Knights Armament version) with the full-auto lower, AEM5 suppressor, A2 buttstock w/ duck tape cheek rest. I'm not gonna lie, I carried it with pride into the chow halls in Kandahar before arriving in Marjah city, I got looks of jealousy everywhere I went, as most thought it was a badass suppressed DMR rifle with an EOTech thermal (we were issued in country). I carried it, among others depending on the mission, but always tried to find a way to get it out and pull overwatch. When in that capacity, we were referred to as "Guardian Angels", where we took archangel callsigns. Anyhow, they issued us 77 gr. OTM rounds, which seemed to do the trick and made for a pretty good urban round. While I didn't get many chances to stretch its legs out like at the schoolhouse, I always thought it lacked more "umph". Now I know some will say "Why not just try to become a "real" sniper and get to carry the big boys (Barrett, M110 SASS, and M40A5),” well I did get to shoot all those but to me they weren't as "maneuverable.” Meaning... you try and put on 120 lbs worth of gear (100 oz hydration pack, 9 loaded magazines, med pack, Kevlar plate carrier with 4 plates, night vision, Kevlar helmet, daypack with food extra water and mission essential gear) You get the picture... those systems are heavy when your out on 3-6 km patrols up and down mountains and Deseret terrain. I also liked operating at the platoon level, getting outside the wire on more intensive patrols, unlike most of the observation and recon missions our 21's were doing, not really getting to do much as if they were engaging targets they weren’t doing their job (during our operation) they were primary recon and report.

To my point and an FYI for some of you, I decided to build MY version of the MK12 Mod 0 (I liked the Mod 0 version better for the handguard). So I looked into Precision Reflex, Inc. as I know they are well known for the Crane MK12's and would be the best place to start. Along the way, .224 Valkyrie was released and after reviewing the ballistics and other data, I decided to take a chance and give the ole MK12 a cartridge upgrade (I don't care to build clones, but an improved version). So I spoke with them about the round and sorta a surprise, but not, they were approached by Federal due to their popular 6.8 magazines. Well PRI thought the same thing I did (before me), and got a few .224 test barrels and are currently looking into building them. Unfortunately, they are still in the R&D stage. So, I started digging into another company I thought might be able to help me out, White Oak Armament, which to my surprise had .224 Valkyrie barrels IN STOCK and were from Shilen and Krieger blanks. So I purchased one and called PRI back, they told me that if I sent them the barrel they would assemble a "made to order" custom MK12 .224 Valkyrie and I thought it was a match made in heaven. That being said, I opted to just order the additional parts and assemble on my own. Below is my parts list:
  • WOA 18” .224 (Shilen Blank) 1/7 Twist- barrel w/ bead blast finish
  • BCM upper receiver w/ full mass BCG and 6.8 enhanced bolt head, gas tube and gas block roll pin
  • BCM Lower w/ WOA LPK minus trigger
  • M48 Gas Buster charging handle w/ combat latch
  • PRI AR15 SPR Straight Top Rail
  • PRI Gen III Round Handguard
  • A.R.M.S #40 Low Profile Rear Sight
  • PRI G2 Flip Up Front Sight with .750 Crossbolt
  • Geissele Super Dynamic Enhanced Trigger
  • Magpul Enhanced Aluminum trigger guard
  • Geissele Maritime Bolt Catch
  • Magpul Enhanced AR Magazine Release
  • Magpul MOE+ Rubber Pistol Grip- Black
  • VLTOR Enhanced Modstock
  • Silencerco Hybrid Suppressor
  • Silencerco Hybrid ASR Brake
  • Silencerco Hybrid Front Cap (.223 version)
  • KDG Sidelok 30mm scope mount
  • (Daytime) Nightforce NXS 2.5-10x42 MOAR and (Nighttime) Pulsar 640 XP50 Trail 1.6x-12.8x Thermal weapon sight
Everything should be in within the next week and I will update with pictures. I finished with optics to tell you guys that after using the KDG sidelok mount for a while, I LOVE IT! Both have been on my SCAR 17 and always return to zero and I take my day optic off quite often to do predator hunting and deer management permits for crop depredation on a friends farm. I get paid to kill deer (Best disabled vet job ever), meat goes to local food banks and feed the homeless programs.

Reminiscing photos attached... the skulls were before the whole call of duty thing and were actually sent to us by a Dad of one of the guys in my squad, who was a biker with a certain group of bikers. We used them on night raids in houses as a psychological effect. I intentionally cropped the other guys out as they are a bit iffy on having their pictures out there, minus the frotto baggins Afghan Army guy next to me.
 

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I’m going to do basically the same except in MOD1 configuration. I have a 5.56 and a .22LR MOD1 already, setup and painted exactly alike(except for different BUIS) and a .224 Valkyrie would be a great addition. I had actually considered committing sacrilege and going with a slightly longer (for velocity without getting too far from aesthetics) and slightly heavier barrel(because I’m weird) and using the same brake/collar for my can. A Valkyrie Mk12 seems very cool, if for no other reason that surprising people at the range.
 
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Wanted to pull overwatch / area surveillance, didn't want to bring a bigger gun. :p
LMAO... Ounces equal pounds... you got me there. I actually rotated between the MK12, M240B, and M249 Para Saw. I also carried a Mk32 ONCE... lol. A six cylinder 40 mm grenade “revolver” is no joke when your ammo count is 40 on the body and 6 in the gun. Plus full battle rattle and I’m completely out of shape now and broke.
 
I have a mod0 and 20" 0~ish without the BUIS. The extra 2" doesn't buy you much with 223. I have kicked around the idea of building a 6FatRat on the platform to up its 600y potential. Your build makes a lot of sense. Looking forward to seeing it come together.
 
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I have a mod0 and 20" 0~ish without the BUIS. The extra 2" doesn't buy you much with 223. I have kicked around the idea of building a 6FatRat on the platform to up its 600y potential. Your build makes a lot of sense. Looking forward to seeing it come together.
Thanks Fatboy, I hope it lives up to the potential that they are hyping it up to. I was willing to sacrifice the extra length and give up a few hundred in velocity. Overall, I would’ve much rather had the range of the .224 Valkyrie and the power of the 90 gr smk Match over the 77 gr OTM. I’m interested in doing a full comparison as the federal lineup has everything I need and want, a long range competition load (gold medal match), Nosler ballistic tip varmint load, the MSR load for deer and other medium size game and a the American Eagle TMJ (same price as decent 5.56 blasting ammo) for messing around. I’m excited that one round with give me such versatility and at a reasonable price. It’s almost like the time I bought my first 12 gauge, lol. I know other rounds exist, BUT IF it lives up to the hype and at least out performs the 5.56 stuff, then it’s a win.
 
once you build a rifle, custom to your "needs" reloading isn't far from your future. Nice thing about the AR platform in general, is swapping to another small frame caliber is pretty inexpensive so if the 224 doesn't live up its easy to change.
 
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once you build a rifle, custom to your "needs" reloading isn't far from your future. Nice thing about the AR platform in general, is swapping to another small frame caliber is pretty inexpensive so if the 224 doesn't live up its easy to change.
I agree 100%. I’ve actually been reloading for awhile and I’m trying to break myself of it for many reasons, but with the main one being time. I already load for a .300 Norma Magnum, .338 LM, 30-06, and .308. That’s because they are the piggy bank breakers, ESPECIALLY the first two. I used to load for 6.5 CR, until I found Hornady ELD 140’s shoot the same exact group size and is within vents of my loading cost. Now, 5.56/.223 and pistol caliber I will NOT load for, as I go through it fast compared to the time it takes me to load it. Maybe if I spring for a progressive setup... maybe. Lol
 
Cool shit dude.. I know what ya mean, theres just something about the Mk 12 IMO. Such an iconic rifle. That barrel should shoot good with the right loads, I wouldve gone with a improved .22 Grendel if its gonna be something besides .223 but horses for courses and such.. good luck.
 
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Cool shit dude.. I know what ya mean, theres just something about the Mk 12 IMO. Such an iconic rifle. That barrel should shoot good with the right loads, I wouldve gone with a improved .22 Grendel if its gonna be something besides .223 but horses for courses and such.. good luck.
I appreciate the vote of confidence, these rounds are all so close these days it's about like trying to choose what brand truck to buy. They all get from A-Z, all depends on the driver.
 
I know a couple of guys that were issued Mk11, M110, 300WM and 338 rifles also but left them in the case and used their Mk12s exclusively. When pressed, one said the ONLY real world advantage of 7.62 to him is penetration through glass or light barriers. But he’s the kind of guy that placed in PRS matches with his Mk12 clone before they separated the 223 gas guns from the 6.5 bolt guns.
 
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Is the barrel profiled for an ops 12/AEM5? Spoke to Ron Alen the other day and he said the AEM5 is rated for 224.

No, the barrel won't be profiled for the ops 12/AEM5 suppressor. I currently have a Silencerco Hybrid can, it works on all my rigs, pistol and rifle. Maybe when the SHARE/HPA act gets approved and cans are affordable and available over-the-counter without the hoops.
 
No, the barrel won't be profiled for the ops 12/AEM5 suppressor. I currently have a Silencerco Hybrid can, it works on all my rigs, pistol and rifle. Maybe when the SHARE/HPA act gets approved and cans are affordable and available over-the-counter without the hoops.


Not to derail but if you’re waiting on any de-regulation to pass before you get another can you most likely will never get another can. At around $650, the AE cans are a good buy as far as I’m concerned. I paid $950 for my 12th model in 2006. If I could have gotten the same can for $650 I’d have bought 2. The hoops aren’t so bad, especially if you’ve done it before and in the light of SS’s kiosk and no Mrs CLEO, besides the delay of them submitting the paperwork after you complete it, it’s pretty painless.
 
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Not to derail but if you’re waiting on any de-regulation to pass before you get another can you most likely will never get another can. At around $650, the AE cans are a good by as far as I’m concerned. I paid $950 for my 12th model in 2006. If I could have gotten the same can for $650 I’d have bought 2. The hoops aren’t so bad, especially if you’ve done it before and in the light of SS’s kiosk and no Mrs CLEO, besides the delay of them submitting the paperwork after you complete it, it’s pretty painless.

Blcouch, there is no need for me to get another can. My hybrid is full auto and magnum rated, can be modified for pistol or rifle, direct thread or QD mount, front caps swapped for specific caliber and is good up to .450 SOCOM. I have pistol pistons for my threaded pistol barrels and all my rifles have the ASR brake on them so I just swap the can over to whichever one I’m shooting. One can to rule them all.
 
Relax, the suppressor was one of the last things to go on that system. The suppressor doesn’t make it a mk12. I carried it and shot at targets that shot back with it as a DMR in Afghanistan. There are better cans and I said this wasn’t a to the T clone, if that were true A LOT of the items on my build wouldn’t be added to it. Not to mention it’s chambered in .224 Valkyrie... I’m making it better based off real world experience with the system.
 
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Blcouch, there is no need for me to get another can. My hybrid is full auto and magnum rated, can be modified for pistol or rifle, direct thread or QD mount, front caps swapped for specific caliber and is good up to .450 SOCOM. I have pistol pistons for my threaded pistol barrels and all my rifles have the ASR brake on them so I just swap the can over to whichever one I’m shooting. One can to rule them all.

Good for you. I wish you well on ‘one can for everything’.
 
I've done something similar, I've always liked the MOD 0 due to the monolithic top rail. This is my twist on the MK12 with a 22" Bartlein Barrel chambered in 6mm FatRat. I prefer the Delta series handguard the the flat bottom in case I'm out without a Bipod.
IMG_20160808_190229600.jpg
 
Old thread here. Any update? Did it shoot well? How far have you taken it? Details, man!

Sorry, I've been away. It shot great! Consistently did 3/4 MOA or better. I have only stretched it out 300 yards off hand supported against a wood beam (realistic shooting) and hit shot after shot on 16 in. diamond steel plates. Unfortunately, I'm looking to fund another project bolt gun and I'm looking to sell it now. Absolutely nothing wrong with it and will probably hate myself for getting rid of it later, but I'm looking to get into PRS comps and need a solid bolt gun and equipment.

Here is the link to the post:

https://www.snipershide.com/shooting/threads/mk-12-mod-0-224-valkyrie.6905156/