MK 12 Mod 1

Ntxglock · Jun 25, 2024

I finally was able to get the MK 12 KAC FF RAS.
Supposed to arrive Thursday. Had been on waiting
list 5 years.

Anyway, I need to select a barrel. I have a spare Colt
upper I plan to use with SF 3P muzzle device.

I want rifle gas. I only find it in Criterion. Others
I’ve looked at are intermediate length including Noveske’s
Rival v2 barrel (17” too).

The Criterion Core is being considered b/c its rifle length gas.
What others are there? Pri? Theirs are Douglas barrels. Not sure
the gas length though. I want it accurate.

Tia guys

KimberGuy · Jun 25, 2024

Centurion

Ntxglock · Jun 25, 2024

Which is the better barrel, Centurion or Douglas (Pri) or Noveske? I have some Noveske
barrels (.308/6.5cm). While I can’t speak to the 6.5cm because I haven't fired that one yet, but I know
the .308’s are accurate barrels.

I’ve read that Douglas is accurate. I suspect Centurion is as well, I love their rails. But I have
the Knights rail coming.

I’m not needing/wanting an exact mk12 clone. I found out that the mod 0 rail is available and I like that rail.
I don’t have anything like that now. I’m really soul searching if I want to use the KAC rail or not.

What’s the downside using mod 0 rail? I’m not interested in the ARMS sights. To difficult to obtain.
Every time I look at their website, notta nothing in stock.

nn8734 · Jun 25, 2024

Ntxglock said:
Which is the better barrel, Centurion or Douglas (Pri) or Noveske? I have some Noveske
barrels (.308/6.5cm). While I can’t speak to the 6.5cm because I haven't fired that one yet, but I know
the .308’s are accurate barrels.

I’ve read that Douglas is accurate. I suspect Centurion is as well, I love their rails. But I have
the Knights rail coming.

I’m not needing/wanting an exact mk12 clone. I found out that the mod 0 rail is available and I like that rail.
I don’t have anything like that now. I’m really soul searching if I want to use the KAC rail or not.

What’s the downside using mod 0 rail? I’m not interested in the ARMS sights. To difficult to obtain.
Every time I look at their website, notta nothing in stock.

Douglas Mk12 18" spr bbl, 7 twist. I bought mine in my mod H from PRI and my Mod 1 from another Hide member. Both are hammers. I think Centurion Arms uses Douglas blanks but not totally sure, you can call them to confirm or deny if no one else does beforehand.

Coejro · Jun 25, 2024

You waited 5 years, do a true Mk12 Mod 1 build. That’s my advice. It’s my favorite AR pattern rifle by far.

Douglas barrels are good.
All you really need is the gas block, collar, and AE muzzle device.

With wait times for suppressors sub 1 week for individuals it’s worth getting the Allen can too.

bfoosh006 · Jun 25, 2024

FWIW.. Criterion also has a Fluted RLGS 18" SS416R Polished. Its Rifle length GP is considerably smaller then the Centurion 18"RLGS I just bought.
Centurion 18" RLGS, .101" gas port size.... The 18" Fluted SS RLGS Criterion has a .092" gas port size
https://criterionbarrels.com/produc...d/ar-15-fluted-contour-barrel/?v=7516fd43adaa

Ntxglock · Jun 26, 2024

Thanks guys.

Can I ask?
1) what is the purpose of a collar? As I understand it, its the threads
around where the muzzle device threads? I’m going with a Surefire 3P adapter.

2) Which is better re: port size using rifle gas with and without a can?
A larger port I suspect?

Ntxglock · Jun 26, 2024

bfoosh006 said:
FWIW.. Criterion also has a Fluted RLGS 18" SS416R Polished. Its Rifle length GP is considerably smaller then the Centurion 18"RLGS I just bought.
Centurion 18" RLGS, .101" gas port size.... The 18" Fluted SS RLGS Criterion has a .092" gas port size
https://criterionbarrels.com/produc...d/ar-15-fluted-contour-barrel/?v=7516fd43adaa

Hey bfoosh! Thanks

The first place I looked was Douglas's website. I sent them an email and they replied
they don't make the (Mk12) SPR barrel.

Then I looked @Criterion. I know they make barrels that shoot as well as I do, LOL.
That .308 I have w/their barrel is my fav.

The next place was Noveske. Their Rival v2 barrel is intermediate gas length and it's 17".
I think I want minimum 18" since this rifles only purpose is accuracy at max range.

Then after I posted I was told Pri. That ruined me. They got stuff, and it's in stock!! Choices!!

Years back, there were no mod 0 rails anywhere at the time I first started down this path. I do like
them and I don't have anything like that. I wasn't really in the mood to do more 5.56's. I'm already having
to separate them (5.56's) to secure them to make space for AR10's.

Now that dam black bug has bit me again. Dam black bugs, LOL. I'm all in for at least one, maybe two of these.
I already have the frames.

jLorenzo · Jun 26, 2024

White Oak makes SPR barrel as well.

nn8734 · Jun 26, 2024

Ntxglock said:
Thanks guys.

Can I ask?
1) what is the purpose of a collar? As I understand it, its the threads
around where the muzzle device threads? I’m going with a Surefire 3P adapter.

2) Which is better re: port size using rifle gas with and without a can?

If you're going with a Surefire adaptor, you're not building an SPR as they all came with the Ops Inc docking collar, which centers the Ops Inc 12th model suppressor as it's an over-the-barrel design. I'd buy the Allen Engineering AEM5 as that's identical to the Ops Inc 12th model and will work perfectly with your Mk 12 Mod 0 (as well as mod1 and H if you decide to convert in the future).

If you purchase a genuine SPR barrel from either Douglas, White Oak Armory, Criterion, etc where the barrel, including the gas port, is all per the original Douglass SPR contract specs then you won't have to worry about proper function with or without a can, assuming your ammo isn't somehow defective, undercharged or over-pressurized.

Ntxglock · Jun 26, 2024

nn8734 said:
If you're going with a Surefire adaptor, you're not building an SPR as they all came with the Ops Inc docking collar, which centers the Ops Inc 12th model suppressor as it's an over-the-barrel design. I'd buy the Allen Engineering AEM5 as that's identical to the Ops Inc 12th model and will work perfectly with your Mk 12 Mod 0 (as well as mod1 and H if you decide to convert in the future).

If you purchase a genuine SPR barrel from either Douglas, White Oak Armory, Criterion, etc where the barrel, including the gas port, is all per the original Douglass SPR contract specs then you won't have to worry about proper function with or without a can, assuming your ammo isn't somehow defective, undercharged or over-pressurized.

Thanks much.

Re: Suppressors. I've always wanted to stay with same brand of suppressor so that way I can use them across most of my rifles. @least 85% of all my builds have Surefire's 3P adapters on them (both AR15 and AR10's). So, I suppose I have another decision to make.

Other than having a true clone of Mod 0 and Mod 1, what would be my advantage by selecting a different suppressor dedicated to only that rifle?

Add: Does Mod 0 and mod 1 require me to select the above (your post)? I understand for the true clone it must be. Can I use Surefire on these barrels? (I may select one of each, Douglas and either Criterion or White Oak barrels).

Coejro · Jun 26, 2024

You can use the Surefire just fine. The AEM5 can is the correct one for the clone. It also has the advantage of being one of the quietest supressors for 5.56 for some reason. It’s still my favorite to shoot because of that. Something about the tone.

nn8734 · Jun 26, 2024

Ntxglock said:
Thanks much.

Re: Suppressors. I've always wanted to stay with same brand of suppressor so that way I can use them across most of my rifles. @least 85% of all my builds have Surefire's 3P adapters on them (both AR15 and AR10's). So, I suppose I have another decision to make.

Other than having a true clone of Mod 0 and Mod 1, what would be my advantage by selecting a different suppressor dedicated to only that rifle?

Add: Does Mod 0 and mod 1 require me to select the above (your post)? I understand for the true clone it must be. Can I use Surefire on these barrels? (I may select one of each, Douglas and either Criterion or White Oak barrels).

It's totally up to you...I run all KAC and Surefire cans on my other rifles so completely understand where you're coming from...But if you want a 'clone-correct' SPR (and there is only three variants of SPR) then you'll want to run the AEM5 (I think Otter Creek also makes a suppressor that is essentially the same thing as well).

ETA - You're basically cloning the "Mk 12 Mod 0" shown in Live Free or Die Hard, used by the French sniper working for the 'bad guys' - it's a neat looking rifle that I believe features a Surefire suppressor instead of an Ops Inc

Ntxglock · Jun 27, 2024

Barrel twist rate: 1/7 or 1/8?

18” barrel. Douglas’s is 1/8, others 1/7.
I suspect 1/8 is gtg?

nn8734 · Jun 27, 2024

Ntxglock said:
Barrel twist rate: 1/7 or 1/8?

18” barrel. Douglas’s is 1/8, others 1/7.
I suspect 1/8 is gtg?

8 twist is fine for up to 77g SMK and bullets of similar bearing surface, weight and other physical characteristics. Douglas SPR barrels are 1:7 RHT but they do offer 8 twist as well.

Jdowns0415 · Jun 27, 2024

Ntxglock said:
I finally was able to get the MK 12 KAC FF RAS.
Supposed to arrive Thursday. Had been on waiting
list 5 years.

Anyway, I need to select a barrel. I have a spare Colt
upper I plan to use with SF 3P muzzle device.

I want rifle gas. I only find it in Criterion. Others
I’ve looked at are intermediate length including Noveske’s
Rival v2 barrel (17” too).

The Criterion Core is being considered b/c its rifle length gas.
What others are there? Pri? Theirs are Douglas barrels. Not sure
the gas length though. I want it accurate.

Tia guys

Get a White Oak Armament Barrel. They're affordable and shoot lights out.

LRRPF52 · Jun 27, 2024

If you have a KAC FF RAS, I wouldn’t waste it on an SPR/Mk.12. Consider doing one of these instead, which are more useful, practical carbines:

NHPiper · Jun 27, 2024

Get a Douglas 1:7 18" from PRI if you want to do a mk12 Mod1.

I have a Mk12 Mod0 and Mk12 Mod1. I am about to toss a Mk5 on the Mod 1 to match the Mod0. It is much lighter than the Mod0. The Mod0 does have a Bartlein 1:7 18" from CLE.

I kind of agree with @LRRPF52 that the NSW Recce is a super unique build. Without realizing, I had actually built a similar rifle using a BCM QRF12 and a Douglas 16" 1:7 from PRI as one of my primary rifles. It's stupid quiet and accurate. A RAS FF Long and a 15.1" barrel would be sweet although I think a 1-8 or 1-10 FFP is a better optic choice than the NSW in the picture above. Personal preference.

Charger442 · Jun 27, 2024

man, i need to paint my Mk12

Malum Prohibitum · Jun 27, 2024

LRRPF52 said:
If you have a KAC FF RAS, I wouldn’t waste it on an SPR/Mk.12. Consider doing one of these instead, which are more useful, practical carbines:

What am I looking at?

nn8734 · Jun 27, 2024

Malum Prohibitum said:
What am I looking at?

Appears to be the Seal Recce rifle. Its a mk12 mod 1 but with a 16" bbl. Uses same ops inc can.

Jdowns0415 · Jun 27, 2024

nn8734 said:
Appears to be the Seal Recce rifle. Its a mk12 mod 1 but with a 16" bbl. Uses same ops inc can.

recce barrel is a 15.1 thats why its basically flush with the FF RAS.

NHPiper · Jun 27, 2024

If I found another RAS that is the direction I would go. Probably different optic setup though.

nn8734 · Jun 27, 2024

Jdowns0415 said:
recce barrel is a 15.1 thats why its basically flush with the FF RAS.

Makes sense

Ntxglock · Jun 28, 2024

LRRPF52 said:
If you have a KAC FF RAS, I wouldn’t waste it on an SPR/Mk.12. Consider doing one of these instead, which are more useful, practical carbines:

What? M4A1?

nn8734 · Jun 28, 2024

Ntxglock said:
What? M4A1?

LOL. Not an M4A1...It's designation is in this thread, you should be able to spot it.

That said, what are you going to do with this build of yours?

LRRPF52 · Jul 1, 2024

Mk.12s are great to shoot from the prone, bench, or off a tripod. Once you go to shoot kneeling, seated, or other alternate positions, they don’t balance well even when slung-up. Seated isn’t too bad if you have a larger torso and a lot of experience shooting that way, but the others are a pain.

This is just one reason why I like the shorter guns suppressed. That 15.1” SEAL Recce Carbine with the KAC FF RAS is about as long as I would want to go once you start shooting positions, and it still isn’t bad to run in the house. Still easy to clear rooms and maneuver with, unlike the Mk.12 (beside the Mod-H).

No appreciable difference in ballistics either. I wouldn’t even do one in 5.56 after shooting 5.56 on steel for the past 30+ years, with another 7 years prior to that shooting water jugs and paper or E-types. Great for 200-300, weak at 400 to where you can barely hear impacts on a crosswind day (which is almost every day for me). If you’re out East of the Mississippi with lots of tree baffling, you should be able to hear your hits better at 400yds, but they will get anemic at 500yds/barely audible even with a small wind. Maybe it’s just my ears.

floridaprepper · Sep 28, 2024

Ntxglock said:
Which is the better barrel, Centurion or Douglas (Pri) or Noveske? I have some Noveske
barrels (.308/6.5cm). While I can’t speak to the 6.5cm because I haven't fired that one yet, but I know
the .308’s are accurate barrels.

I’ve read that Douglas is accurate. I suspect Centurion is as well, I love their rails. But I have
the Knights rail coming.

I’m not needing/wanting an exact mk12 clone. I found out that the mod 0 rail is available and I like that rail.
I don’t have anything like that now. I’m really soul searching if I want to use the KAC rail or not.

What’s the downside using mod 0 rail? I’m not interested in the ARMS sights. To difficult to obtain.
Every time I look at their website, notta nothing in stock.

I just got a Centurion MK12 mod 1 18" SS BL w/Centurion Brake, flip up sites, with a billet upper and lower, 15" Centurion Rail, 2 stage on what they call a "Sniper" trigger. Looks like its going to price out at about $1500.00, includes everything except a stock. Does that sound like a fair deal? Changing subject, do you know anyone that has any reloading data on the MK12 round, latest version MK262, 77gn Ballistic tip Sierra Boat Tail. I am trying to get Alpha Munitions to make their version brass case for 5.56, these cases are over built and incredibly stronger than any other brass. These cases can take a hefty charge without having to worry about them letting you down. I have been using Alpha Munition 308 win brass both large and small primer. I have a batch of 50 rounds that I have reloaded 26 times at well over 55,000 psi, at 2715 fps on a 208gn Hornady ELD. Once more, I have not had to trim cases. Under a microscope the cases show no signs of any fatigue. The primer pockets are just as tight as when they came out of the box. Anyway if they will make the 5.56 cases it would allow taking that 77 gn bullet to new heights safely. Well here I am running on, but I would appreciate getting your opinions and if you have seen any reload data for that 77 gn Sierra in MK262 configuration.

floridaprepper · Sep 28, 2024

Oops, typo, 65,000 psi on the 308 win chamber pressure, per Quick Load.

longshot2000 · Nov 14, 2024

Ntxglock said:
Which is the better barrel, Centurion or Douglas (Pri) or Noveske? I have some Noveske
barrels (.308/6.5cm). While I can’t speak to the 6.5cm because I haven't fired that one yet, but I know
the .308’s are accurate barrels.
ck.

First quesiton is whether you will run suppressed. Centurion is Wilson barrels (as I recall), but our testing failed the suppressor fit, as did DD, BA and others. Criterion is good if you have the right barrelsmith make it. We use a handful. Douglas is your best bet. Very accurate, and we have CLE profile, so the suppressor fits. You can get from us or PRI. Same barrel.
https://charliescustomclones.com/mk12-douglas-18-stainless-steel-spr-profile-barrel-1-7-5-56-nato/
https://charliescustomclones.com/mk12-douglas-18-stainless-steel-spr-profile-barrel-1-7-5-56-nato/

We also have some Bergara barrels made for lighter loads, as the twist is 1:9, but a reasonable option, and a small savings.

Keep in mind the mission defines the barrel and the barrel defines the rifle. If you are working backwards and saying you want an accurate rifle that is Mk12 like, then you want an accurate and dependable barrel that is profiled for all the AEM equipment. Now, Centurion will accept the AEM hardware, just not the suppressor. That may have changed. I know Alex at Trajectory is trying to get some of the third party barrel profile companies to change their profile.

fedupflyer · Nov 15, 2024

Mine is starting like this

jLorenzo · Nov 18, 2024

floridaprepper said:
I just got a Centurion MK12 mod 1 18" SS BL w/Centurion Brake, flip up sites, with a billet upper and lower, 15" Centurion Rail, 2 stage on what they call a "Sniper" trigger. Looks like its going to price out at about $1500.00, includes everything except a stock. Does that sound like a fair deal? Changing subject, do you know anyone that has any reloading data on the MK12 round, latest version MK262, 77gn Ballistic tip Sierra Boat Tail. I am trying to get Alpha Munitions to make their version brass case for 5.56, these cases are over built and incredibly stronger than any other brass. These cases can take a hefty charge without having to worry about them letting you down. I have been using Alpha Munition 308 win brass both large and small primer. I have a batch of 50 rounds that I have reloaded 26 times at well over 55,000 psi, at 2715 fps on a 208gn Hornady ELD. Once more, I have not had to trim cases. Under a microscope the cases show no signs of any fatigue. The primer pockets are just as tight as when they came out of the box. Anyway if they will make the 5.56 cases it would allow taking that 77 gn bullet to new heights safely. Well here I am running on, but I would appreciate getting your opinions and if you have seen any reload data for that 77 gn Sierra in MK262 configuration.

22.8gr AR Comp, 24gr Varget, mk262 is probably using a ball double base powder bur I don't know.

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