How Effective is the MK12?

[sua175]

no the solicitation was originally just for a upper, but dudes in units quickly realized that they wanted match trigger. At least that is what I have been told by old timers who were around back then.

[RyanB]

It was originally the Special Purpose Receiver but they had issues with the original M4A1 buffer (H) on auto under some conditions and so they got the M16A1 lower.

[skp]

It was originally the Special Purpose Receiver but they had issues with the original M4A1 buffer (H) on auto under some conditions and so they got the M16A1 lower.

I don't think the mk12 has a happy switch?
Chris Kyle stated in American Sniper that he would sometimes pop the mk12 upper on his M4 lower to gain full auto capability.

[gun71530]

I don't think the mk12 has a happy switch?
Chris Kyle stated in American Sniper that he would sometimes pop the mk12 upper on his M4 lower to gain full auto capability.

The first MK12's were built on M16A1 lowers.

[skp]

The first MK12's were built on M16A1 lowers.

Yeah but those were prototypes.

[LRRPF52]

A lot of good points in the thread. The mention of quality optics in the hands of someone that knows how to use them gets overlooked by a lot of people, but can't be emphasized enough. Glad to see it mentioned here.

Good glass plus variable magnification, especially anything 6x and higher, is a huge advantage for soldiers who are the type that take the initiative and report up what they see to small unit leaders in proximity and position to act on that info.

The Leupold 3-9x36 MR/T, 2.5-8x36 MR/T, NightForce 2.5-10x24, USO 1.8-10x37, and similar compact variables with good glass do a lot for a DM and his unit. More on glass later, but it is arguably more important than the guns themselves.

The 2 biggest things that I take away from the DM skill set (which is really a historical squad sharpshooter that was removed from the MTO&E back in the 1950's) are:

* Increased situational awareness for the dismounted Infantry Squad provided by a well-trained observer/shooter/communicator, with quality optics

* Increased effective range on enemy targets of opportunity, as well as increased hit probability within normal engagement distances for the riflemen



Mk.12 Pros and Cons
I think the Mk.12 brings several pros and cons in these two areas, but the tool aspect gets put into perspective when you accept the importance of the training aspect, at about a 15/85% ratio, with the training obviously being the most important.

Positions
From solid supported positions, the 18" SPR AR15 does really well. Once you get away from a lot of nearby solid shooting structures (like in urban and built up areas), and have to shoot from field positions, it starts to suck a bit, depending on the size of the shooter. Bigger guys with the right build can sometimes set up into hasty positions better, but it is more difficult to shoot for a lot of guys, especially with the barrel profile and a quad rail handguard. That increased overall and forward weight is also an issue in higher altitudes, where oxygen is limited. That is the main trade-off between a 14.5" or 16" carbine, and an 18" medium/heavy target gun with pineapple rail.

Accuracy
Accuracy that I have seen from the guns is excellent, and .5 MOA is not uncommon with a Douglas Super Match pipe with Mk.262, probably in excess of what most shooters can even exploit outside of a relaxed, prone supported position with rear bag. Velocity is also pretty hot with Mk.262, pushing the upper edge of 5.56 NATO pressures. I would argue that the Mk.12/Mk.262 is probably the most accurate self-loading sharpshooter system ever fielded.

My thoughts on the system are that an 18" gun might be ok for units conducting dismounted patrols working from vehicles in urbanized areas, with the understanding that the DM's primary role as a rifleman in the CQB fight is going to allocate him to the tail-end of any maneuver elements, but does really well for support once in position. A 16" gun would allow both, and since the distances are usually well within 600m, the case is even stronger.

Areas for Improvement
The main area I see for improvements in this regard are lightening up the gun, still using high quality pipes, but with a much lighter profile. If you select quality steel, with a concentric bore, square faces, true threads, etc., with someone that knows what they are doing for the reaming process as well, there is nothing wrong with the JP 18" and Lilja Wasp profile pipes. I would easily reach for the lightweight/heavier fore end pipe from those two over a medium/heavy contour without thinking twice about it.

For a training environment on KD ranges, the medium/heavy contour makes a lot of sense for class volume, but not for carrying and shooting positions. Even that said, these JP and Lilja lightweight/heavy for end barrels shoot very well for me over extended range sessions. Combined with a lighter weight handguard and 2-point quick-adjust sling, the 18" guns start to become very manageable.

Ammunition
One area where performance can be picked up if a shorter barrel is used is the BC of the projectile. The 75gr A-MAX has really demonstrated that for me, even though I was of the school of thought that it couldn't be loaded mag-length in the AR15. A guy showed up to one of my DM Courses in 2013 with a few hundred loaded up, with a light crimp to take away the exposed mouth. I thought we were going to have major issues with him and his loads, but he ended up being the one impacting steel in very adverse weather conditions with an 85% hit rate out to 600yds. That .435 G1 BC of the 75gr A-MAX combined with a lightweight 16" MLGS carbine (Centurion pipe), even though it would "only" hold 1.5 MOA, was the set-up to beat, and that was going head-to-head with 18" .223 Wylde and LMT MWS .308 guns shooting Match ammo.

I think the new Tipped 77gr SMK with .420 BC, or even the TSMK 69gr with .375 BC would make a 16" DM Carbine as potent as the 18" with Mk.262. Use a light/heavy for end profile, quality barrel with tight twist, maybe nitride it for longer throat life, use a very lightweight handguard like the BCM KMR, and look at an optimized compact optic with better than decent glass, rugged features, smart reticle design, and you would have a series of improvements for the SPR/Mk.12 legacy moving forward.

Bigger Picture
The bigger challenge with the whole mess is getting the Army to support its own doctrine and MTO&E with the training at the unit-level, as well as providing a solid platform and ammunition to support that 15% side of the equation. The AMU has been carrying much of the burden in this regard, God bless them, and that spirit needs to be internalized and codified at the Combat Brigade and Division Levels, as well as in the Officer and NCO Training and Professional Development Systems.

A 2-Day DM Course for IBOLC candidates should be part of the POI, run by AMU. Since the DM is one of the EM slots in the Infantry Squad, his Team Leader needs to be an SME already on the duty position as well, and retain the capability as a DM in the TL slot. Where will this skill set be taught, maintained, evaluated in the ARTEP and common skills tasks? Those are the issues I'm looking at. Sorry for the rant, but this is something very near and dear to me.

[HDHNTER]

That was a good read. I've had my Mod1 for many years and love the rifle... but it's the Mod Holland that I reach for when the yotes get the livestock worked up in the middle of the night. 16" + 12th is noticeably more pleasant to carry for an extended period of time vs 18".

[TehLlama]

That was a good read. I've had my Mod1 for many years and love the rifle... but it's the Mod Holland that I reach for when the yotes get the livestock worked up in the middle of the night. 16" + 12th is noticeably more pleasant to carry for an extended period of time vs 18".

If you think that setup is awesome, 16" with 14th is a real peach - take 2" off both the barrel and the can. Not that I'm biased or anything, but a 9lb rifle that shoots that well under solid glass means the hardware can be sorted easily compared to making the doctrinal and training changes to really run that to its best. To a degree it does work pretty well to have the most math/shooting inclined guy in the squad be the DM (especially if there's a dedicated weapon system to augment that ability), but I'd put even more emphasis on the communication end of that deal. For the continuing COIN environment I experienced it was a truly excellent tool before the selector leaving 'Safe'.

Complete druthers would be an M4/M4A1 MURG with a 16" tapered contour SS barrel (the MSTN-Noveske would be the benchmark for that at the moment), a goldilocks optic (2-12x32mm Leupold Mk6 type setup with Horus/CMR reticle), and a can with a 6" OAL (reflex if possible, OPS 14th or an SF FA556 shortened by one baffle) - net result is something the same length as an M16, maybe half a pound heavier, and being the sort of 600m swatter Dano's talking about with minimal tradeoff compared to a carbine, and requiring a 7.62 weapon system to do much more. Unless some seriously intelligent people start re-working the training curriculum and empowered small unit leaders to make decisions about what toolset to draw from the armory, then this is a better solution than mass fielding M110/M110-C setups.

[HDHNTER]

Agreed regarding the KAC. Love my SR, but she's a pig. I alternate between an AEM2 (M4M) & a 15th on my 15-22 "Mod H". It's wearing an SSA in addition to the AE/Ops can so legit enough for a rimfire plinker. Shoots damn good & hollywood quiet w/ subs. It's now wearing an SPR grip as well, nice combo w/ the MK12 platform IMO. I wouldn't mind having a 14.5" Recon profiled for the AEM2 w/ the PRI tube, that would be a kick-ass pairing w/ 77gr TMK's.



5.56 bigger brother



& a little Mod1 love since I'm posting pics

[mig1nc]

Ah, I remember when you posted that one on Facebook. That is one hell of a slick pinker.

I'm thinking of doing a Holland style build but using my 15th (I don't have a 12th).

I need V7 to make a titanium barrel nut for PRI tubes