Mk12 Mod 1 in AA 6.5 Grendel

[taggor]

It's time I shared my build....

This is how my 18" AA build started in 2010. I knew that i wanted a DMR type rifle but really was unaware of the specifics for either version of the Mk12 until later.



I was facinated with the Mk12 Mod 0/1 projects having read quite a bit on them including the detailed Chapter in "The Black Rifle II" and at that time decided to use some of the components used on those rifles. Q: So why a Grendel? A: I wanted the longer reach of the cartridge and had built enough 5.56's and was not interested in another at the time. Perhaps the most interesting part of the project was the barrel work. It was done by Ron Allen from OPS Inc. He made the collar and brake to fit the AA 18" barrel. Designed to fit the 12th model supressor (That I should be able to consider by mid 2012). In addition he cut a shim for me to time the brake correctly. A real pleasure to do business with.



So, after two years of "research" and learning (more like misdirection) more about what the "real build" spec's were for the Mk12 Mod 1 (subjective, of course, to which version carried by which branch of the services and the amount of $$$ allocated to said project! That means no select fire for me). I took a few "liberties" here and there other than the caliber. I rebuilt the rifle to where she is now at the beginning of 2012:





I haven't taken out this version to the range yet because I am still working on it (I need those Zero stop turrets!) but, I am sure it will shoot just as good as the other variations it has been through. Maybe a bit better with the "high-end" glass (That is if I can find the best 123gr/Powder combo... haven't found it yet... and quit using so much caffeine!). So while this build will never be "accurate" to the true Mk12 afficiando, I offer it here on this forum which is where it belongs anyway. Hope you all enjoy and get inpired as I have!

[LRRPF52]

Excellent rifle and pics. I think the SPR configuration is a close to perfect match for the Grendel/AR15 system, as well as the application in an ideal world. In the practical world, the 77gr 5.56 Mk262 is the best choice for logistics and the performance is actually quite favorable, but the SPR Grendel is a great option for civvies.

[Variable]

Beautiful rifle Taggor! I really like it. I hope she shoots like a dream for you when you finally put her through her paces.

[taggor]

Thanks for the "props"! I really do enjoy this rifle!

As far as how it shoots....the rifle shoots fine... me, well I am working on it!

I have been working on some of my hand loads. This was before the Nightforce scope. Most recently I was using the Midway BSA Tac-Mildot scope prior @ 12X and I got these results @ 200 yds. Not too much variance from 28.0 grns - 28.3 grns. I had been working up the load and didn't get to shoot the 28.4 or 28.5. Also of note is that I was planning on using Sierra and Lapua 123gr too but, ran out of time at the range. So perhaps more later (in the appropriate thread of course!)

[Drifter]

Excellent build.

[Whelenon]

Very nice and the background provided is excellent. Thanks for sharing.

[texasgrunt]

Nice Stick! Any plans to try out the factory 123 AMax or 123 Scenar ammo? I'm curious what results you would have with those two.

Grunt

[taggor]

Thank you for the "props" Drifter, Whelenon, and texasgrunt!

texasgrunt


Nice Stick! Any plans to try out the factory 123 AMax or 123 Scenar ammo? I'm curious what results you would have with those two.

Grunt

I have tried the AA 123 Scenar, Hornady 123 A-Max, Wolf 123 SP, and the Wolf 120 MPT factory loads but, my records keeping is not the greatest and at those times I was using iron sights on the gun @ 200 because that's all I had. So while the shots are "on" (That would be on a TQ-15 target five ring and quite a few in the 4 and a couple outside!)the group sizes are nothing to genrate awe! Certainly not precise shot placement not to mention slamming the trigger at those shots down and to the right. That's with AA 123gr Scenars.



When I have the Nightforce "up and running" I will try to be a bit more diligent with my records and share here but, @ $350 for Zero stops, it's going to be a while. Not to mention how long the wait might be for the upgrade. At least it shouldn't be like waiting for a tax stamp but, I have been wrong before.

[Bronz]

yes This is a project I have been thinking about.

[taggor]

yes This is a project I have been thinking about.

It's been, and still is, a lot of fun for me. I think you will enjoy the project if you are into this kind of build. Interestingly enough When the 6.8 cartridge was developed there was a Mk12 prototype developed in 6.8 which echoes the Mod 0 found on page 157 of "Black Rifle II." So why not a varient in 6.5G!? At least that what I thought. Good luck with your build!

[icanhithimman]

Thats looks awsome. I have the same set up for the most part. Just waiting for the right barrel to come along.

[usmc1371]

nice looking rifle.

[taggor]

Thanks for the "props" icanhithimman and usmc 1371!

Thats looks awsome. I have the same set up for the most part. Just waiting for the right barrel to come along.

What sort of barrel are you looking for?

[icanhithimman]

Well Like yours I suppose, I must look through the sites of all the barrrel manufactures once a week. I look for something I may have missed. I'm looking for something in an SPR profile, most barrels I see are to long for my liking and to heavy. I want army or marine spr profile not some bull barrel thing.

[taggor]

Well Like yours I suppose, I must look through the sites of all the barrrel manufactures once a week. I look for something I may have missed. I'm looking for something in an SPR profile, most barrels I see are to long for my liking and to heavy. I want army or marine spr profile not some bull barrel thing.

Mine uses the AA 18" barrel and bolt with the mid-length gas system. I am really pleased with it. Some folks have gone with a 20" and cut it down to 18" while retaining the rifle length gas system. I would imagine that that is more what your looking for. I am not aware of anyone making a barrel with the exact profile your looking for chambered in 6.5 Grendel but, I am not all knowlegable with many of the different offerings out there. Post it up on the main boards and maybe one of the members here can help you.

[JAGONH]

That is a nice build, maybe in 6 months you'll see my little frankenstein!

[taggor]

That is a nice build, maybe in 6 months you'll see my little frankenstein!

Thanks!

Maybe in a year you'll get to see the OPS Inc 12th model can for this build! Haha.

[taggor]

Well, somtimes you can't leave "well enough alone." Since posting the older pictures I had experimented with an A2 stock and a Burnsed loop as well as sling loop adapters and rail covers. While I wait to have Nightforce Zero Stop turrets installed on my scope. Still saving for that. The current setup is different from what is pictured here but, hope to post some in the future. A little desert background!

For anyone who is interested in the parts spec it is as follows:

Lower:

Nodak Spud NDS-16A1 lower
DPMS lower parts kit without trigger
Colt magazine release button (it just feels better than the DPMS)
A1 "E" type buttstock
Standard rifle buffer
JP tuned buffer spring
Geissele SSA-E trigger
Ergo rubber ambidextrous grip

Upper:

AA 18" mid-length barrel/bolt stainless and bead blasted
LMT AR-15 semi bolt carrier
OPS Inc. Brake/ 12th model Suppressor adapter, collar and timing shim (custom made by Ron Allen)
Essential Arms upper with hard coat
Brownells upper parts kit with mid-length gas tube
Badger Ordinance Mk 12 gas block
PRI Gas Buster charging handle with big latch
KAC FF RAS rifle length hand guard PN#99167
KAC bipod adapter
KAC M4 front sight PN#99051
KAC 200-600 meter rear sight PN#98474
KAC Swivel mount assembly (2) PN#98720
Daniel Defense 1 o'clock offset mount

Accessories:

Harris S-BRM bipod with leg notches and KMW pod-loc (current version)
Blue Force Gear VCAS sling and buttstock adapter (still not sure it's a better sling than a padded VTAC for certain applications. IMO)
Nightforce 2.5-10 X 24 with #22 A.R.M.S. high rings

What's left? :

Aimpoint Micro T-1
A.R.M.S. #31 mount for the T-1
OPS Inc 12th model suppressor in .308

[LightningII]

outstanding.
You have basically built the rifle I've been visualizing for two years.
I need to do a little more than visualizing in the $$ department, though.

[taggor]

outstanding.
You have basically built the rifle I've been visualizing for two years.
I need to do a little more than visualizing in the $$ department, though.

Lightning, yeah the $$ is tough. I have been working on this project for two years myself. A little here and there. That's the way it has gone for me too. I plan to post new pics when I get some of the final parts. I am sure your build of the Mk 12 will come along. It just takes the old "time and money" Thanks for the props!