To set the context for my question, I need to explain my background. I never served in a military or LE capacity, so if I confuse terms and roles, please forgive my ignorance. As a connoisseur of military history and historical weaponry, I can’t help but love the basic concept of the MK 12. Having grown up shooting NRA Service Rifle matches, I have appreciated what good ammo and a well-built AR-15 is capable of. After discussing some basics with friends, I wanted to ask the forum what they think a modernized Mk 12 would look like for an urban environment, say for Ramadi or any major urban center in the Western Hemisphere.
Has the concept merged with the “Recce” rifle?
Are we going with an 18’’ or 16’’ barrel, and at what contour?
Would you mount a fixed stock or a specific type of M4 aftermarket stock?
Mlok or a Picatinny rail?
What magnification range would you consider necessary? Is there a specific go-to optic
Bipod or not?
Singe stage match or two-stage trigger?
If you have an example or a personal rifle that might fit this criterion, please explain your thought process behind it. If there are readers with experience behind the Mk 12, please feel free to provide your two cents on the rifle or the intended role.
Thanks!
This is my culmination of 25 years of trial and error going back to a trimmed FSB Colt 6731 barrel under a free-float tube (not rail just a tube), various Mod 0 and Mod 1 iterations and a whole bunch of HK 416 DMR setups…
A 16" DD CHF barrel more than suits my needs and has no trouble with 2/3 IPSC’s out to 880y and 1/3 IPSC’s to 600y. Picked one out of a batch that turned out multiple sub-moa groups.
Rifle is geared to run 0-600y at minimum.
I’ve run 1-4x’s up to 5-20x on SPR’s and 1-8x fit the above parameter fine even though target ID and hit calling at 500-600y with 8x top end can get a little sporty. Despite the 1x CC feature, I like the piggy-back Micro red dot as a sighter at distance (when optic is left 4-8x), a backup sight, and CQB option.
Went with the Harris over the Atlases that I normally use on precision guns due to weight and simplicity.
I added the wrap as a temp barrier in hot/cold months and it acts a little like a bag as it has some give when resting on barricades
The rear monopod flat I use as a rear bag rest
Slimmer sling with a forward mount to be of actual use for positional shooting.
20-round PMags with use of a +5 adapter. Sounds stupid but 30-rounders don’t let the rifle sit without extending the bipod legs. This is the Goldilocks compromise to have a shorter mag profile without dropping 33% capacity. 25+1 is a fair compromise for this.
Barrel length is negotiable. If you want short, get short. If you want the most juice, go long. I see no point in going beyond 16" for practical reasons
The beauty of a small-frame is the capability for the size. Longer barrels and fixed stocks complicate that. With all that you can bolt onto a CTR stock, save the PRS stock for the SR25’s
Magnification is a subject for the distance AND size of the target. 0-600 is where the system shines brightest. 1x per 100y and divide by the size in target in MOA to find what your minimum mag top end should be.
Rail and trigger stage are subject to personal preference.
For this style of build is a simple tube a bad idea? What do you give up with a Harris on a sling stud?
Nothing wrong with simple/slick.
How much are you wanting to load the bipod? The stud/clamp method of attaching a Harris pales in comparison to the Badger, Larue, or even ARMs mount style that replaces that hardware…so much so that it shifts the failure point to the legs/joints.
If you never shoot from anything but a bench its fine, but if you start throwing your weight around you will.
Are these for the simple FF tube or do they require a rail?
Personally, for my own spr-ish setup, I went a midlength 16" Kreiger CLE chamber barrel, VLOR upper receiver and 15" MK4 handguard. The lower is standard, nothing fancy with a BCM LPK, SSA-E and a PRS Gen 3 stock with rifle buffer and spring.
I originally ran a NXS 2.5-10x42 but switched to a ATACR 4-16x42 to see if I could use more magnification. It’s nice to have, but not necessary, IMHO.
I have both a 20 inch SPR type and a 16 inch recce rifle. I went with a 20 inch partly because I used the M16a2 and I liked the Marines concept with the SAM-R. I’m using a PRS gen 2 now, but was using fixed Magpul rifle stock which I’m tempted to go back to. Scope is a Leupold MK5 3-18 great scope btw. I will admit it’s on the heavy side but I like the 20 inch for just a little flatter trajectory, though an 18 would probably be fine. Geissle SSA-E two stage is also what I’m running. It’s a fun rifle to shoot and extremely accurate, I wished I could have had it when in the service. 16’s are great also and very versatile. When I first started doing matches I was running a 16 inch BCM with a non free floated HFB. Range went to 550 yards had no problem keeping up with bolt guns and longer barreled AR’s. 16, 18,20 they all have their merits and handicaps.
Sent from my iPhone using Tapatalk
Here’s another serious question: Does a 16’’ have an advantage over 14.5’’ in a DMR/SPR type setup?
To me, the SPR was to take down things from 200-600 yards. I used my JP upper with 18inch, rifle length adjustable gas and LMOS operating system and hydraulic buffer. Oh- so sweet recoil impulse and the ability to see splash and take follow-ups. I’ve topped it with a 3-15Premier when focusing on long distance, before the 1-8/10x scope came out. I had a 3-15 when a 2-10 would be the more natural choice. I run a 1-8 on it now. To me, the SPR was a long range capable, hence the 18inch barrel and big scope. I think the scope technology getting with the 1-8/10 scope has made 2-10s redundant. 1-8/10 give you ‘red dot’ and the ability to reach out with a tree reticle on higher power.
Two stage G-trigger, slick JP fore-end with a Harris Bipod.
I just went through this myself, updating/modernizing a MK12.
The heart of the rifle is a Douglas SPR 1:8 SS barrel. V Seven upper receiver, V Seven 16.5” Enlightened Rail, Nightforce 2.5-10x24 in an A496 mount. Geissele SSA trigger, Dead Air Keymo flash hider and a SOPMOD stock.
Is it heavy? Yeah, kind of, sitting at 9.75 pounds. It does what I need it to do, it’s accurate, fairly smooth shooting, and it handles heat well.
My next updated rifle will be a RECCE. Almost same setup as above except using a V Seven 16” 1:7 SS barrel.
I went a even different route.
With the evolving “threat engagement area’s” of both Urban and Rural and the fact that where I live, on 300 acre farm, then drive 6 miles and I’m in a city of 15,000 or 15 miles the other way and in a city of 250,000, my engagement area’s are different, but the same.
I’ve been following what Lucas at T-Rex Arms has been doing and it got me thinking and this is where I arrived at with my choice in “SPR” concept.
13.7in Ballistic Advantage Midlength HANSON profile 5.56
Dead Air Armament Sandman-K and accompanying Muzzle Device to get 13.7 to 16.1in(without can).
Vortex 2-10 Gen 2 Viper MRAD
Badger Ord COMM-1 with offset Sig Romeo 5 (I’ve beat the hell out of this just as you would an Aimpoint… and it lasted longer than my T1 did with same abuse!)
BCM lower, BCM 13in MCMR (shaved the front down to work with 13.7 barrel)
Geissele SSA-E
With this setup, I can go from an alley fight at 50ft to engaging targets with accurate fire at 500-600 (getting hits at 600 on the farm). Its short enough to not be unwieldy at street fight distances and retains enough velocity to be combat effective at 600.
I took my modernized MK12ish gun out to the range a few months and was pleasantly surprised how much I missed shooting it.
I forgot how easy it is to shoot and make quick corrections on follow up shots.
This gun started out as a mod0 project. Updated it awhile back to make it more user friendly.
WOA 18” SPR barrel
URX4
Surefire Socom brake/suppressor
Bushnell LHRS 3-12
Sent from my iPhone using Tapatalk
If I were to put together a DMR/SPRish rifle now, I’d put a forend with a Swiss-ARCA rail on the bottom. I have one on my bolt gun and that is a slick way to move hand stops and bipod mounts and other gear along the bottom of the rifle. Plus it gives a flat surface for just general resting.
Cool setup. I’ve seen Lucas’s setups for a while now. I love seeing what everyone has come up with. I guess the major question I would have to ask if I was setting up a rifle or upper would be whether I need to emphasize mobility or range from a fixed position.
Boom!
You just illustrated why the SPR as a concept is a technological dead end and doesnt need “modernizing”. Because a modern AR with a decent barrel and 1-8x or 1-10x scope can do the SPRs job while being shorter, lighter and without compromise for fighting up close.
Remember the original SPR came out of the need for guys wanting a “Sniper M4” which was supposed to be closer to the Recce concept which bloated into the SPR. Such a heavy and long gun was never wanted in the first place.
The SPR is for cloners and the dust bin of history, no one needs to be carrying around that weight. Need something optimized for long range? Better off going with a large frame gun like a CSASS. Which is pretty much what the military is doing.
Precisely… and I’m reconsidering the 2-10 with offset on this rifle. Honestly reconsidering LPVO’s on 5.56 guns period, the weight vs slightly gained capability just isn’t there I don’t think.
This optic setup might end up on the market. I wish I hadn’t sold my NX8 1-8, it was shorter and lighter than anything else LPVO I’ve used thus far. Between that NX8 and the EOTech Vudu 1-6, those are just good optics.
A good 1-6 or 1-8 like the NX8 and Vudu, run it on 1 power and its close enough to a red dot I don’t notice any difference up close and if necessary, I can engage at distance on 1x and just use holds like I would a normal dot. Then dial if needed/time allows, no need for offset.
With the luxury of both an excellent 18" and 16" setup, I’m pretty much always going to choose the 16" setup. Spend that mass budget on a can, optic, offset optic, and run better ammo, you end up achieving so much more. By the time I’ve slapped a can on my 18" setup, I might as well be running another caliber, the primary advantage that offers is that it’s a tack driver and has a bit more reach, but practically that brings very little over running 3.08 or 6.5 caliber stuff for the same area, just runs the same cheaper ammunition. In practical terms, the SPR only existed because of this shared magazine capability with M4s, as that’s the most reach you can achieve using those, but why any units with the option want to run a caliber with more legs inherently, despite the weight and capacity penalties.
I’ve had the most luck running a 1.1-6x optic on the 16" setup, although I could swap on a 2.5-Nx optic on there, my current placeholder is a cheaper period correct Leupold on the 18"… I find this less valuable because I’m no longer filling a niche role within a larger unit.
As far as detailed hardware - a good trigger (SSA-E) is a worthwhile investment, having a QD bipod is always a nice multiplier, but most of the time I’m not using it, just firing off a backpack. A solid multi-use stock is great, which rail is mostly irrelevant, any modern one is great, and slick is usually preferable. Muzzle device - if a can is an option, make that a priority, otherwise, most anything will do. I’m still partial to the old Vortex ones.
QD bipod
If you’re not trying to replicate anything in particular, realize that overall versatility, and ability to perform well at rock-throwing distances will ultimately be more valuable, so a 1.1-Nx optic is likely going to serve you better overall, and anything you can do to keep the overall weight manageable is going to pay dividends. A good basic light, proper sling mounting, and solid trigger are musts, but everything else can be to preference.
This gun is a somewhat strange hybrid as well. Honestly, the only reason the higher magnification optic makes any sense in my context is it does double duty as a patrol rifle and sees fairly regular use alternating with a Tikka Tac A1 .308 as an overwatch/sniper rig covering an LE entry team. The additional magnification and larger objective/exit pupil make a non-negligible difference in PID (as compared to a 10x LPVO) in low light at a couple hundred yards. If it was not used in the latter capacity, an LPVO wins out almost every time just for the weight and 1x ability…and it’s not like the LPVO wouldn’t be viable at all even in my particular context; I’ll fully acknowledge there’s a part of me that just likes bigger glass.
That said, for me there’s honestly only about a 7 ounce difference between this rig and something like a Gen III razor, because I’d run an offset RDS regardless and generally prefer to have a bipod on anything that’s not a dedicated entry gun.
-Gun is a 14.5” BCM BFH ELW, which is a somewhat strange profile for this application but this barrel is pretty great for what it is; holds a reliable 1 MOA for 5 shots at 100 and helps with balance overall.
-Badger/Harris bipod
-Modlite OKW w/Unity Hot Button
-Vortex Viper PST Gen II (decent for what it is but it’s a placeholder until Leupold finally has Mark 5s back in stock…)
-Nightforce A496 mount
-Aimpoint H2 in an Arisaka mount
-Geissele SSA-E
-pinned Warcomp (Socom Mini II in NFA jail)
Interesting setups in the thread I have been looking at 1-6 and 1-8 LPVO’s to pair with a red dot on my 16 inch gun, which currently has a 1-4 on it. But this makes me consider something like a Nightforce 2-10 with a red dot as a overall setup for this rifle, also looked at the option of a mounted red dot with the scope in my backpack with quick release mounts on both, you could switch out in a few seconds if needed. I already have a home defense rifle with a red dot so this would be more of a do it all setup
I love the practical responses. Whenever I find myself able to invest in another rifle, I will take y’alls feedback as the basis for my own build.