I am thinking of building a Mk 12 clone, either mod 0 or 1. Any info or advice?
If your hearts truly set on a 18" barreled SPR I would stick to the Mod1. While I personally love the looks of the classic Mod0’s PRI forearm and ARMS top adapter rail it is now a dinosaur. It has way too many individual parts, un-needed weight, and screws that can loosen up on you. You would be much better off in the long run building a Mod1. It is a much cleaner, lighter, and simpler design. Just substitute the expensive and hard to find KAC parts for Daniel Defense, Tango Down, Troy, and LaRue parts. The Noveske 18" SPR Barrel would also be perfect for this project.
Agreed with Dinger on that.
For a handguard and upper, the VLTOR VIS-3 looks like it will be hard to beat 
Say whay ever you want about the Mod 0 but it has a more flexible method of mounting optics.
Ok, I’ll be the contrarian here.
I have a Mod O and really like it. The VIS would be more ideal than anything else available and is what I would use next time.
That said, I prefer the Mod O version to the Mod 1.
The PRI carbon forends are very high quality, light, rigid and offer flexibile configuration of the rails. Though it is debatable whether neccesary, the extension rail which locks onto the forend is more rigid and offers a continuous, uninteruppted top rail mounting surface. Properly installed the screws are not coming loose.
“Screw-phobia” should not be an issue.
SPRs and AR15s have quite a few threaded assemblies- pistol grip, buffer tube, rear sight, magazine catch, flash hider, rings, light mounts, bipod mount, etc…
Another benefit to the top rail is that standard height rings can be used, which leaves less of a pedestal effect between the scope and rail.
Not that it matters, but I find the Mod O appearance to be unique and attractive.
Mod O or 1, both are great rifles, it makes me happy to know that in this case our guys are issued a the finest available equipment.
If you are interested, I am selling the upper from the gun below…
Here’s the specs:
This is a custom upper built similar to the SPR Mod 0 spec.
Round count = 50 Black Hills 75gr .223 match-grade ammo. Held less than 1 inch at 100yds. Proper break-in followed. Functions flawlessly.
ATN 5X33L Scope has range finding reticle and bullet drop compensator for .223/5.56mm.
White Oak Armory A4 Upper
White Oak Armory Stainless Steel Barrel 18" 1:7 SPR contour (Turned from Wilson Match Grade blanks)
White Oak bolt carrier group with bolt
Black KG Kote on barrel (Done by ADCO)
YHM Phantom 5C2 flash hider
YHM Front Flip Sight / Gas Block Assembly with bayonet lug
PRI Gen 3 carbon fiber rifle-length free-float tube
ARMS #38SPR PEQ2-3 17 5/16" long rail
ARMS #40L Flip-Up rear back-up sight
ARMS #22 30mm quick-release ring mounts, medium height
ARMS #32 quick-release bipod mount
Harris 9-13 bipod
ATN 5X33L scope with .223 bullet-drop compensator
Complete upper group as described = $1600
Complete upper minus scope, rings, bipod and bipod mount = $1250
The change from Mod0 to Mod1 was made for good reason.
EOM
My two pennies…
I recently struggled with the same dilemna. I would say that VA Dinger makes very good and valid points.
The best point I would make is that you can save money and get “better” parts with a MOD 1 type. Here’s what I went with.
18" Compass Lake Doulglas SPR 1:8 black kg bbl
COLT m4 Match lower
COLT m4 upper
LaRue 13.2"
LaRue gasblock
LaRue SPR mount
Leupold 3-9x36 Illuminated Mildot scope
OPs Inc 12th Model brake and collar
Ergo grip
Sopmod stock
TangoDown single point mount
Harris bipod
Ultimately get what you’ll be happy with
Hey!!! I thought we were buds. I resemble that remark.
KAC lower
Magpul PRS, MIAD
Colt upper
Colt BCG and MP bolt
ARMS rail
PRI CF tube, front sight gas block
NF 2.5-10 in LT SPR mount w/ LT J-Point mount and J-Point
Noveske SS 18" SPR barrel, SS, poly, 5.56 Match chamber
OPS Inc 4 port brake
Raptor bipod
SF M962 in LT mount
Thats blaphemy with a KAC lower.
I have a Mod 0
I prefer the Mod1 version (not just cause I am a KAC cheerleader).
Kevin, how do you like the GripPod?
Dinger – the only use I have for it is on a M249Para - with the RAS on it you pretty much have to shitcan the bipod – so the gripod is useful in that role as it gives you the vert grip/bipod. On an AR - I find it of NO use. I use a KAC vert grip on all my guns – and if I use a bipod I use a TD or a Harris.
I dig the blankie.
Agreed on the bipod choice. The GripPod is neat, but I haven’t actually found a use for mine. It’s a decent vertical grip, but it’s not all that great at being a bipod. The TangoDown, on the other hand, is the heat. I use the hell out of it.
GF’s brother in law did if for the last christmas gift exchnage – she saw I have an American flag hanging in my room here and decided I need to remember that I came from Canada…
I tried the Gripod on an AR in class and found it WAY too front heavy (esp since I like my grip out front). I got it for free as a trial item and we found a use for it on the SAW RAS –
I don’t know which is better, but the Mod 0 does it for me. If I were going to use the Knight’s gear, I would make it a SAM-R with a 20" barrel. However, this Mk12 Mod O clone sports a Douglas SS 1/10 twist 6.8 SPC barrel from WOA.
I too prefer the Mod 1. I have all the parts except I’m waiting for the VIS rifle length and JN’s SPR contoured barrel.
Some thoughts:
I’ve used the original SPR with the PRI parts and Leup 3.5-10x, as well as the Mod0 and Mod1 using the Leup 3-9x.
For pure shooting I like the original SPR and Mod0 and have an early one built by the original Crane vendors. The Mod1 is a better field rifle.
However, currently, there are better options than either one.
Many of the best builders have moved away from the rifle length gas system on 18" barrels in favor of mid-length. There is virtually nothing that an 18" SPR can do that a 16" Recce/Recon can’t do about as well, given equally good barrels and optics. Rather than a Mk12 , these days I’d go with a good 16" Recce–probably a Noveske using a LaRue rail and an NF or S&B scope in a LaRue SPR mount.
Kinda interesting that there are two schools of thought for barrel lengths: 10/14/18 or 12/16/20 and I’m tending to lean towards the latter these days.
The “Intermediate” length system has proven to work very well on the 18" guns… it is slightly longer than the Mid-Length and tuned for the SPR barrel – It takes care of the little quirks the rifle length system has on the platform.
I am with you in the belief that the 16" barrel and mid-length gas system is the best “do all” setup for the platform though.
Here is my Mk12 Mod 0.5, as I do not believe it represents a Recce carbine any better than it does the MK12 series. Although, it does sports a GTS recon barrel, the 1/7 twist works wonders with my 77 gr handloads.
