Building an MK12 1000 Yard Rifle

You think I live in the south mainly flat lands around here. I am gonna try got a friend that has some pasture land that is over 1000 yds and he said I can try my luck out there.
 
Ok guys, I am building a MK12 rifle that if I am correct will shoot out to 1000yds. What are your opinions on this shot is it possible using a 5.56 rd?

That is really too far for the .224 bullet. For example, According to JMB Ballistics (JBM - Calculations - Trajectory) the 77 grain SMK traveling at the muzzle at 2700 FPS would at 1000 yards have a drop of 520.9 inches. Your scope would have to be able to handle 49.7 of adjustment in MOA. The speed of the bullet at that distance would be 972 FPS. This is well below the speed of sound and the bullet will squirrel prior to hitting the target, really dropping the accuracy. If there was even a slight wind of 5 mph, you would have a drift of 155 inches. Ouch.

The bullet is just dropping too much. I would think that anything within 600 yards is more appropriate for that round.
 
1000yd is a LONG poke for a mag-fed 77gr bullet, even at 5.56 Mk.262 velocities. I've shot my FrankenSPR as far as 900yd with 77gr Noslers @ 2670fps, and with a density altitude around 1000' it really struggled to get there and splash was all but nonexistent. I think I fired 10 rounds at a 10" target and got one hit; had it been a man-sized target I probably would have gotten a few more hits and most assuredly pissed him off ;)

Single-feed it 80-90gr SMKs or Bergers and the game changes quite a bit...but you'd still need to have realistic expectations about the capabilities of that case from a gasser.
 
If you live near sea level, you will need to single-feed one of the VLD bullets behind a stout charge with temp-stable powder.

Even then, you are pushing it with an 18" gun. It's doable with a very limited selection of bullets.

Your best bet will be in hot weather, high altitude, with no less than a G1 BC in the mid .400's.
 
I shot my Mk12 mod 0 at 1000yds earlier this year. I caught some crap from the fellas, because it was supposed to be a vintage precision rifle shoot. Anyhow, single feeding Black Hills 80gr SMK will get the job done, well enough it surprised the hell out of me.
 
I put two of 20 or so on a silhouette at 1000 using a stupid accurate MSTN built 17" 5.56 w/ MK262 and zero wind. Surprisingly, I was significantly more effective at 1000 during the same trip with my 16" 6.8 using factory Hornady 110BTHP. I haven't even tried for a 1000 with the 5.56 since then.

That said if I were building a dedicated 5.56 for long range use I would use a 24" barrel and a single feed follower to feed 75gr AMAX or 80gr Bergers. If I was set on a MK12 build I would probably keep it inside 800 unless I felt like being frustrated by not making hits.
 
I would tend to think a MK 11ish build would be a more appropriate 1000 yard rifle, I'm not saying can't shoot a MK12 that far but the MK11 would be a better tool for that job....
 
Not to say it can't be done but what is the point? As mentioned above, terminal ballistics are none existent, round is dropping like a rock so again, wrong tool for the trick. Same rifle could be a tack driver at 500-600 but 1k is outside of the calibers capabilities.
 
Yep. Lower that 1000yd hope to 600-700yds and ul be tickled pink with its ability to shoot the lights out on a 12" plate.

You don't have the velocity or BC to do it.
 
I tested an HCS Mk12 Mod01 near Dugway Proving Grounds in the fall of 2011 and posted the results here on SH. I got it out to 1200 yards with Black Hills Mk262 OTM 77gr ammo at 5000 ft in 50-60 degree temps. The rifle was unsuppressed at the time. At that range it still blew through a pine 2x4 and 3/4 inch chip board and left a 9 inch cavity in the clay and mud. Not key holing or tumbling. It shot consistently out to 900 yards. From there on out, hitting a man size target required a lot of elevation (17.2 mils at 1200 yards) and max windage with a NF 2.5-10 x24 scope. At best it was a 20% probability at 1200 yards, about 50/50 at 1000 to 1100 yards, and 80% or better at 900 yards. A man eater at 500-600 yards. In my experience the max effective range for the rifle is 900 yards. I can now hit the 800 yard uphill target at the PMAA range consistently having shot 6000 rounds through this Mk12 Mod01 rifle. It shoots even better with a Ops Inc 12th model suppressor. More velocity, better accuracy, quiet, real easy to shoot.
 

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OP,
I first competed with the AR15/M16 in the '70s when the M14 ruled; the platform has come a very long way since then. Puts a smile on my face every time I get a chance to shoot it at distance. As posted above, an over-mag-length 5.56MM 80gr. VLD fired from an 18" shoots very well at 750yds. & appears to have had the needed MV to make it to 1000yds. accurately. Did not shoot it at 1000yds. as I did not have a 20 MOA base. If you are not using a suppressor, a 24" or 26" barrel would be much better suited. Double based TAC was used for the added MV, probably the same reason the BHA MK 262 MOD 1 cartridge uses a double based spherical powder. Just had to watch barrel temperature/chamber time to control ES/vertical stringing. A thermally stable propellant would be easier to work with as long as you can get the needed MV out of it. 02.

80gr. VLD over 5.56MM NATO pressure TAC in LAPUA brass seated over-mag-length to 2.390" fired from 18" 1x7.7 SS Krieger/CLE at 750yds./70F/200Ft. MSL : MV 2822 FPS with SD 6.24

 
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I live at 1000 feet in elevation and generally shoot at 3000 feet any above. I have what I would have wanted for a MK 12 with a polygonal barrel so I get just a touch more velocity from it than a button rifles or cold hammer forged barrel but I have shot a 10" steel plate at 800 meters and know I could at least hit silhouettes at 1000. It can be done but depending on what you are shooting at, the atmospherics, and some other factors, it is definitely a long poke! It would definitely be a nice challenge for yourself though.

While writing this I remembered that I have a buddy that had a Larue PredatAR 16" with what I think was a Walther Lother (or something like that) polygonal barrel and he shot his 10" steel plate and shot about a 4" three shot group with it. Granted 4000 feet and no wind on a relatively hot day but consistency is king. Too many people get caught up in other factors. As long as you have a consistent load out of an well maintained accurate gas gun with a scope with enough travel and accurate enough tracking, you can do it.
 
This is all great information! After spending about 4300$ on parts and about 2000$ on optics all that is left is to get it in and put it together. I'm stoked to give it a try and put that notch in my belt.
 
Yep with that kinda cash id have looked into a sr25 clone if 1k is what I wanted to touch in a mk12 style platform.

I have yet to take my 7mm rem mag to 1k yet lol although easily doable, my crappy rangefinder only gets me to 600-700 most days.
 
Obviously youve already decided what you want but a good bit of the High Power competitors using AR15s are shooting 6mm`s. 6mm Fat Rat, 6mm AR/AR Turbo/AR Turbo-40, 6mm WOA, etc. All of them will fit well in an AR15 and AFAIK the Grendel-based 6s(Fat Rat, 6mmAR, etc) have the ability to fit 105s at mag-length with a good 2750-2850fps MV depending on barrel length. That`ll have no problem making it to 1000. Basically talking about 6BR performance in a case that fits the AR15 a bit better.
 
Take a trip to FT. Perry and watch the guys do it with open sights with 20" barrels. (NO SCOPES).

While its obviously doable, they're doing it because the rules restrict them from using any scope. Its more of an accomplishment and requires much more skill but if they were allowed to use scopes I guarantee you they would be. Hes not competing and doesn't need to ignore 100yrs worth of technological advancement.
 
" After spending about 4300$ "

You mind sharing your parts list? 'Franken built' Mod 0 and HCS Mod 1 together are less than that.


Id like to know that parts list too. My mk12 mod 1 with no expense spared ran me about 3500$ total including optics just waiting on the can so for 4500$ I'm fully set...

6500$ on a mk12 is a bit over kill. I could have had a mod 0 and a mod 1...
 
" After spending about 4300$ "

You mind sharing your parts list? 'Franken built' Mod 0 and HCS Mod 1 together are less than that.

BARREL DOUGLAS
GAS BLOCK PROTOTYPE
MUZZLE DEVICE LANTAC DRAGON

UPPER RECEIVER
BILLET UPPER RECEIVER PROTOTYPE
BCG YOUNG MANUFACTURING M16
CHARGING HANDLE PROTOTYPE

LOWER RECEIVER
BILLET RECEIVER SAN TAN
LOWER PARTS KIT W/O FCG LMT
RECEIVER EXT TUBE W/ CASTLE NUT/END PLATE DSG ARMS
BUFFER SPIKES T-2
AMBI SAFETY SELECTOR MAGPUL
BUFFER SPRING JP ENTERPRISES
GRIP MAGPUL MOE+ GRIP
BUTTSTOCK B5 SYSTEMS
TRIGGER GEISSELE SSA TRIGGER

RAIL SYSTEM
RAIL GEISSELE MK4
BIPOD HARRIS ENGINEERING
BIPOD MOUNT AMERICAN DEFENSE
BACK UP IRON SIGHTS (FRONT)TROY IND
BACK UP IRON SIGHTS (REAR) TROY IND

OPTICS
NIGHTFORCE

Did I over Pay? Thought I was getting a pretty good deal. the prototypes are from a friend of a friend that has not released them yet and I am getting them from him so I can't say anything until after the shot show.
 
It can get there depending where you shoot and atmospherics. I would highly suggest you consider a 20, 22 or 22" that are still pretty compact specially a 20" with a short 1" brake.
I pulled some old math for you. Also try double tap 80gr long range load.

Your Input Variables
Ballistic Coefficient 0.395 Velocity (ft/s) 2887 Weight (grains) 75
Maximum Range (yds) 1200 Interval (yds) 100 Drag Function G1
Sight Height (inches) 1.5 Shooting Angle (degrees) 0 Zero Range (yds) 200
Wind Speed (mph) 10 Wind Angle (degrees) 90 Altitude (ft) 500
Pressure (hg) 29.53 Temperature (F) 70 Humidity (%) 0.78
Ballistics Results - AR15 -Krieger 5.56 18" - Hdy. Superformace 75gr
RANGE (YARDS) VELOCITY (FPS) ENERGY (FT.-LB.) TRAJECTORY (IN) COME UP IN MOA COME UP IN MILS WIND DRIFT (IN) WIND DRIFT IN MOA WIND DRIFT IN MILS
Muzzle 2887 1388 -1.5 0 0 0 0 0
100 2663 1181 1.7 -1.6 -0.5 0.8 0.8 0.2
200 2450 1000 0 0 0 3.2 1.5 0.4
300 2247 841 -7.5 2.4 0.7 7.4 2.4 0.7
400 2054 703 -21.9 5.2 1.5 13.7 3.3 0.9
500 1871 583 -44.6 8.5 2.5 22.3 4.3 1.2
600 1699 481 -77.3 12.3 3.6 33.7 5.4 1.6
700 1540 395 -122 16.6 4.8 48 6.6 1.9
800 1396 325 -181.5 21.7 6.3 65.8 7.9 2.3
900 1270 269 -258.8 27.5 8 87.2 9.3 2.7
1000 1165 226 -357.7 34.2 9.9 112.4 10.7 3.1
1100 1084 196 -482.3 41.9 12.2 141.2 12.3 3.6
1200 1022 174 -636.4 50.6 14.7 173.1 13.8 4
 
" Did I over Pay? "

You paid more than I would, but your parts list is nothing like I have. I skimped a little I guess. Mod 0 is RRA upper/lower, WOA Barrel, RRA 2 stage and I didn't buy the (expensive) 1 piece rail that's supposed to be on there... Mod 1 is HCS upper, Palmetto lower, SSA-e. Plain Jane A2 stocks...

E, is that the MV you were getting from an18" barrel?

Yes. That is the MV of the superformance load. Another hot one is the 80gr double tap. 2690 for a super efficient 80gr bullet.
They get out there but I highly suggest 20" minimum for the long shots.
Let me know if you need more data. I have almost all commercial ammo known in the USA tested in all kind of barrel lenghts
and configurations. So over the years I have been collecting lots of data. Whenever I setup the chrono to test any new loads, wildcats or whatever
I always bring carbines and rifles to test commercial ammo and record the data.