View Full Version : MK262 mod 1 load data help
I'M looking for anyone that has loading experience cloning the MK262 round the military uses from black hills.
Here is what i have worked up so far and just trying to find more data, does anyone have any other load data to add?
I have had good results using IMR 8208 XBR powder, my results are an average 2,665 FPS with a standard deviation of 16.88 out of an 18" SPR wilson combat barrel 1:7 twist using 23.1 grains, LC brass, and CCI#41 primers. Seating is at 1.869" to ogive using 77 grain SMK w/cannelure. Chronograph placed @ 5'. shots taken in 68-91 degree temps.
This powder is a short extruded type, also the factory new Black Hills (red box)69 grain OTM is short extruded powder coming in at 24.2 grains, 2012 WCC headstamp.
CFE223, and varget don't even come close to the velocity i was looking for to match the MK262 without a compressed charge, Tac powder works well but changed with temprature, IMR 8208 xbr is not near as sensitive to temp changes like the other above mentioned that i have used.
My groups are consistently under 5/8"@ 100 yards.
P.S. If you attempt loading per my data, do so at your own risk. 23.2 is the max recommended charge for 8208 xbr@55,000 psi.
You can likely shave your SDs in half with Wolf or Tula primers. And you might even improve your groups.. although, you're getting pretty good results there already.
A few of us here are running 23.4 or 23.5 gr of XBR with 77s. XBR is a little tricky. It'll turn on you with no warnings up around 23.8. I'd shot a bunch of that, then switched lots, and all of the sudden was getting a bunch of blown primers and heavy case head swipes.
I do have #7-1/2 SR bench rest primers(Remington) but haven't tried them yet, i have mainly been checking consistency of this powder so far.
do you think those primers will be sensitive to primer strikes and or shrink my SD's? Do you show pressure signs at those charge weights, and i imagine those are compressed charges?
Thanks for the information
We've burned through at least 10k of those primers with no issues. The WOLF SRMs are supposed to have a thicker cup, but I use any an all of them with no problems.
At 23.4, I get no pressure signs, and am getting 2730ish velocity from a 20 Colt. That charge is not compressed.
Can I ask why you are trying to clone this ammo? I would much rather stack holes at a little slower velocity than have a .75moa group that achieves a certain velocity. Accuracy > velocity.
I'm running 23.4-23.5gr XBR under 77gr SMK/Nosler CC's and CCI450's or WolF SRM's. I haven't had a chance to run anything over a chrono in quite a while, but this load is a frickin laser.
FWIW, I was getting 2,700fps with 24gr Varget and CCI450. I imagine this XBR load will be fairly similar, if not a little faster.
That round (MK262) was designed for the mark 12, why would I not want to clone that round after spending 2K plus building the mark 12 SPR. Besides, the whole fun of reloading for me is creating an identical round or close to black hills that is designed for my rifle.
I want 5.56 cartridges. If you're loading what you're saying you're doing the same thing too. 24 grains is a slightly compressed load in my experience and I'm wanting the velocity without a compressed load if I can help it. 8208 XBR meters better than varget because it's short extruded instead of long. Also Under 5/8" groups is laser accurate in my opinion. But that is my reason for wanting to get close to the MK262 round
That round (MK262) was designed for the mark 12, why would I not want to clone that round after spending 2K plus building the mark 12 SPR. Besides, the whole fun of reloading for me is creating an identical round or close to black hills that is designed for my rifle.
I want 5.56 cartridges. If you're loading what you're saying you're doing the same thing too. 24 grains is a slightly compressed load in my experience and I'm wanting the velocity without a compressed load if I can help it. 8208 XBR meters better than varget because it's short extruded instead of long. Also Under 5/8" groups is laser accurate in my opinion. But that is my reason for wanting to get close to the MK262 round
Hey, there's nothing wrong wanting to clone it. I was just curious. Your brass will not last as long with such a hot load. Mk262 is a VERY hot load. It looks like you are getting great groups though.
Early on, I wanted to clone Mk262 too. I was chasing a certain velocity and not getting the results I wanted downrange. Nowadays, velocity is important to a certain extent, but it is not the end all. With Varget and XBR, I kept upping the charge until I got the accuracy I wanted, whether it's over or under recommended, I didn't really care.
I arrived at 24gr of Varget by seeing the results downrange. It is a compressed load with no pressure signs and excellent results, just a pain to work with. My XBR load is not compressed, but the tail of the 77gr SMK's do hit the powder just as it is fully seated.
As long as you work up to it and really understand what you are doing (not you specifically, generally speaking), I see no problem with going over a max recommended powder charge or using a compressed load as long as there are no pressure signs. I do doubt you will achieve Mk262 velocities with an extruded powder without a compressed load. Remember though, you will have diminished brass life with 5.56 pressure loads.
Whiskey&beer
09-27-14, 13:46
Have you shot MK262 out of your barrel so you know exactly what velocity you need to get your goal on your loads?
Sounds like you've got a good load right there, but I'd bump the powder to 23.4-23.5 to see what you get, and definitely try Wolf and your 7.5 primers. I personally didn't like the #41 primers, they brought up my ES and SD's and they are more expensive.
If you really want play around buy some M193, pull the bullets and dump the powder, and put your powder and SMKs in and jump up another few grains to see what you can get consistently. That way you got brand new brass and crimped primers to help with pressure. Matching 262 is going to bring you into high pressure.
my apologizes for not really knowing what you meant by your post. i'm getting the performance down range and very close to what velocity i'm wanting. I'm no just chasing speed, i am willing to sacrifice speed for accuracy. i haven't had to yet.
I have room to play on what i can charge the cases with, not sure i will need to.
so far i have been able to reload the brass 5 times with the lot i am using with no excess signs of case head bulge, or gas leaking past the primes pockets. i will say that beyond 5 loads the primer pocket isn't as tight but does seal off, i'm not working them past 6 reloads. That will change if i up my charge from where i am now.
Yup, i always work up loads. Having something blow up in my face doesn't sound like much fun. when it comes to my reloads i am OCD
talking to black hills they test this round(MK262) from a 20" barrel @ 2,750, so i figure if i am averaging 2,665 FPS now and work up a load to 2,700 FPS out of my 18" that's about where i plan on stopping as velocity is concerned as long as my down range isn't effected. I'm wanting both but ultimately accuracy is more important and always has been.
i am unable to get the factory new black hills of this load to test in my rifle, i know that's the best way to match the load but well calling them to confirm what 77gr OTM they use and barrel length is all they can give me, the powder has been by the book and tested, tested and yup tested.
no i have not, i wish local shops had some on shelves. best i have seen in black hills red box is the 69 grain OTM, i have purchased two boxes ($50!!!)<per box. That round screams out of my rifle at 2,841 FPS with sub moa groups.
i think i will try my 7-1/2 matched up with my powder charge to see if i can lower my SD's, if it does then i will work up the powder charge checking both velocity and downrange. if my groups open up i will go back down. I did just recently change out my timney 4 pound trigger for a timney 3 pound, maybe that will help groups too? that's up to me.
Ramshot TAC at around 24 gr will give you about 100fps over varget with only a slight loss in accuracy.
Thanks, I have found that Tac and 8208xbr work well for me, I have used varget and it doesn't meter as well as 8208 and doesn't give me the velocity I'm looking for. I'm looking for velocity and down range accuracy. So far both have worked well(tac and 8208) I'm just stepping up on the charges to see if anything changes down range, or I get pressure signs. My main goal is to find out other results people have had with powders I haven't used that may come close to what I'm getting.
I just received two new boxes (red box) of black hills 5.56 77 OTM (MK262 mod 1) and can't wait to shoot them.
I was surprised that my chosen seating depth for my hand loads was the exact same as theirs (1.869" to ogive) but the powder is a ball powder which I didn't expect at a weight of 25.6 grains(hot). I have not shot them yet to see how they perform in my rifle, but soon enough I will and will come back to tell my results.
I just received two new boxes (red box) of black hills 5.56 77 OTM (MK262 mod 1) and can't wait to shoot them.
I was surprised that my chosen seating depth for my hand loads was the exact same as theirs (1.869" to ogive) but the powder is a ball powder which I didn't expect at a weight of 25.6 grains. I have not shot them yet to see how they perform in my rifle, but soon enough I will and will come back to tell my results.
I'm curious to see what your results are with the MK262. I never could get that load to group better than an 1MOA with my 16in DDM4. I had to go with a lighter bullet (75gr) and drop velocity down to 2600fps, but now 0.25-0.30 MOA is easily obtained when I do my part. Was the consistency of the seating depth of the Black Hills on par with your hand loads?
I'm shooting out of a Wilson combat 18" spr barrel with a 1:7
My hand loads are .628"@100 yards when I do my part. Velocity is 2,702 FPS
Their seating depth was within +/- .001 throughout the rounds I have, I randomly chose and didn't measure them
all. They are out of the same lot.
My hand loads are as consistent as theirs for seating depth.
As soon as I shoot me a group of 10-20 I will post the results, hope I do my part.
Greentimber
10-11-14, 13:02
24.0 8208xbr behind a 77gr Nosler or SMK gives 2760fps and ~3/4 MOA from my 18" Compass Lake SPR. 23.0 (corrected from initial typo) was very slightly better accuracy but I'd rather have the 150+ fps. No pressure signs.
Whiskey&beer
10-11-14, 13:15
You loaded up 77's with 26.0 of XBR??? That's gotta be way beyond over pressure! No way in hell I'd be shooting that!
You loaded up 77's with 26.0 of XBR??? That's gotta be way beyond over pressure! No way in hell I'd be shooting that!
That has to be a typo. I've got blown primers and case head swipes at 23.8.
That's what I'm thinking it was, but whatever it is I'm not loading that hot.
Greentimber
10-12-14, 01:53
That IS a typo. Should read 23.0 grains gave 2600 fps! Good catch. Thanks.
I would edit that post just in case someone happens not to read the correction and attempt loading that overcharge.
Just my two cents if it matters.
My Elite Hbar 24" loves 24.0 XBR with 77 SMK's @ 2880 ft/secs... To avoid the case head swipes the use of a JP adjustable gasblock and Tubb CWS & CS Flatwire Spring has helped. Tula or Wolf SRM gives single digit SD's. 23.2 grains gives 2775 ft/secs in the Colt with the same level of precision. My 18" Rock Creek custom barrel which is melonited likes 1/10 of a grain less for 2775 ft/secs, but 23.2 is more accurate in the Rock at 2680 ft/secs. Loads are in LC '06 brass and cartridge overall length is 2.255" Further to control the apparent pressure signs I pay extreme attention to how much I am bumping the shoulder back on the brass. Simply put I use bolt-action tight .001 - .002" of headspace clearance. These rounds cycle just fine.
Lot to lot powder variation was an issue until I was able to acquire a substantial amount of a single lot.
Always work up, or be prepared to blow up your rifle!
Colt with Wolf averaged SD's of 10 to 11
The rock creek barrel had one string where the first 6 were zero, but for the 10 rounds finished at 5. averages about 7 to 8. Oehler 35P data collector.
Okay everyone, went to the range today and shot a few strings of black hills ammo. 29 rounds of 77 OTM (mk262 mod 1) and ten rounds 69 grain OTM.
I think everyone here knows my rifle. Here is an image of my results string one and three are the BH77gr OTM and string two are BH69gr OTM. I know I did only 9 on the first string, had a guy in my ear and didn't count right. As expected the heat increased my average velocity on the third string to 2,723.75 FPS as compared to the first nine shots of the first string only averaging 2,691.99 FPS. Either way it seems my reloading is just about matching the velocity of black hills mk262 mod 1 out of my rifle.
29004
Here are 10 of my hand loads using Sierra 77gr OTM with 23.1 grain 8208xbr 1.869" to ogive and #41 CCI primers cases trimmed to 1.750" and crimped. I do plan on upping my powder charge and changing primers.
29005
Don't ask for the grouping size, it's nothing special when you have someone on the range shooting a 50BMG just a few lanes away from you. I know you're not supposed to take out flyers but if I take those out the group falls at .822" first string and 1.870 with the flyers. Third string no flyers is .634" with flyers 1.635". The first string had five flyers and the third string had four flyers. These two are results of the mk262 mod 1 from black hills. Take out my flinching when a 50BMG shoots next to me and these rounds are fantastic Also this shoots 1.5" high at 100 yards and also rings the 10" gong at 300 yards without adjusting scope elevation.
As you have already learned speed alone is not the answer. Using the right powder will give you the greatest precision at a velocity near to what a factory round yields. It is your individual barrels harmonics which will determine where that accuracy node lies. The change in primes will be beneficial to your pursuits. Try not to oversize the brass as well.
Good luck
I agree, at this point where my velocity stands I'm playing with the charge not so much for velocity but to see if my groups open up or shrink. Yesterday's results were more my error than that of the load itself.
While I would like to see 2700 FPS averages it really depends on how it performs down range at this point. My fourth string loads were my hand loads, not sure what happened with those two that shot over 2,700 fps, but had those been like the other eight shots my E.S. Would have been very little and SD would have been single digits most likely.
Load and shoot, repeat.
Just an fyi, my old load of 24.0gr Varget, CCI450, 2.255 OAL averaged to exactly 2,700 fps...
I gave up on this load because Varget really sucks to work with and there are much better powder options out there.
That's why I use 8208xbr. It's easier than varget to work with and meters well enough no to be a pain for an extruded powder. I will say that the black hills 77 OTM (mk262) with a 2013 head stamp have a ball powder in them weighing in at 25.5 grains!!!! considering they shoot around the 2700 FPS range out of my rifle and I'm shooting 23.1 currently and almost matching them something else must be adding to the weight that doesn't add to the velocity. Or I need to look up max loads for ball type powder.
I recently got some XBR and finally loaded up a few to test today. Mark recently told me about the 23.4gr with Wolf SRM load for 77gr SMK's and I've been following this thread. Today I shot 77gr SMK with 23.1gr of XBR and Wolf SRM primers with 3/8" group size at 50 yds. I also shot 23.4gr with 5/8" group at
50 yds. Haven't chronoed them yet and hope to shoot at 100 yds on Sat. I'm shooting a DD V1 with a Vortex 1-4.
I am going to load a few higher just to find my barrels sweet spot. it seems like 23.1 is doing great for you. Let me know what you chrony it at. Your group might open up some at 100 yards.
Mark has been very helpful with the information he has given. Hope mine has been half as much help as his with the addition of the result of the black hills MK262 I chronographed.
Somedays are really good trigger days. DDV1 with Vortex PST 1-4 shooting the 77gr SMK's with 23.1gr of XBR. One 5 shot group was just under 1/2" with another group of 3/4" at 100 yds. I also chronoed 10 rounds with an average of 2,652fps. I think I've found a load that my gun likes. I'm also liking the SSA trigger.
Thanks guys for all your help.
Eric
I had debated gong with the SSA trigger but chose timney 3 pound instead. That's some good groups, and about the same average velocity I'm getting.
I did some 300 yard shooting with the black hills 69 OTM a couple days ago and it grouped 1.58 inches.
With a zero of 100 yards, my optics are adjusted up 1.5 moa for 200 yards, and plus 2 moa for 300 yards(3.5 moa from zero)
Hi, saw the thread title and remembered I had come across some loads. It is from 223reloads.com, duplicating nato cartidges section (http://www.223reloads.com/home/223-5-56-info/223-5-56-reloading/duplicatingnato) everything below is copied from that website.
"If you want an MK262 mod 1 duplicate, try:
77gr Sierra Match King, 25.3gr Varget, CCI 400 primer, and LC brass - NOTE: THIS LOAD EXCEEDS SAAMI SPECS. USE IN NATO OR WYLDE CHAMBER ONLY. USE AT OWN RISK. - 2780~ fps in an 18" SPR barrel
FYI: Nosler 77gr will shoot a little faster than Sierra 77gr with the same powder charge. It is probably due to the fact that the Nosler has a shorter base to ogive length and thus has less bearing surface with the bore."
"I exactly duplicated the M262 load with TAC, but it is very hot and I changed to N540.
It was 26 grains of TAC driven by a Magnum Primer with the Nosler cannelured 77 grain bullet. This came out at over 2750 fps from a 16 inch barrel. I didn't have a problem with it but some of the primers were flattened.
To dup the M262 using available powder I use the much more expensive N540 and Varget.
That said I use more TAC than any other powder because there is no reason to load this hot for plinking, triggertime, drills, and even shtf with 62 grain bullets.
For TAC I suggest 25 grains with a normal primer driving 62 grain bullets. That will more than approximate M855 and be easy on your gun. I load 2 different 62 grainer bullets, pull down M855 and Golden West 62 grain with cannelure.
--
There have been posts on Mk262 recipes before. I've posted the one I developed for my 18" SPR when I still had it.
NOTE: The following data exceeds SAAMI specifications and can be dangerous to use in certain rifles.
Sierra Match King 77gr BTHP
25.3gr Hodgdon Varget
LC Brass
Winchester SR Primer
Developed in a White Oak Armament 18" SPR configuration with a Wylde chamber.
Note: At the time, I was using Winchester SR primers. I would recommend Remington or CCI instead.
Any load that will give you Mk262 performance will exceed SAAMI specifications for .223. Thus, you're not going to find any published commercial data that will meet Mk262 velocities.
You shouldn't use anyone's Mk262 'recipe' straight up.
If you want to make your own Mk262 clone ammo, you NEED to get a chronograph and work up the load appropriately. Don't kid yourself thinking you can just use someone else's recipe or the commercial data and guestimate the proper load to meet a specific velocity. The Mk262 pressures/velocities are pretty hot and you're going to need to carefully find the right load for your specific rifle. And when you do find the correct load for your specific rifle, you need to reconfirm the load every time you go to a new lot # in bullets, powder, primers, or cases.
Also, that Nosler load quoted as mine was not confirmed to be 2650fps in an 18". That is my load I use in Service Rifle and it clocks 2740fps in a 20" Service Rifle barrel. I would estimate that it shoots 2650fps in an 18", but I have never clocked it in a 18" barrel.
--
Ramshots 5.56 data for the 77gr bullets show (20" barrel)
Bullet weight: 77 grain HP.
Start load: 22.1 grains (2525 – 2625 Ft/p/sec)
Maximum load: 24.5 grains (2750 – 2850 Ft/p/sec). <62000 Psi"
Test, test, test, test, and test some more. That's reloading when it comes to developing a hand load just for your specific rifle/pistol.
Whiskey&beer
11-01-14, 12:23
If you really want to duplicate MK262 then I'll just say again - buy a box or two of the actual 262, chrono it out of your rifle so you know exactly what speeds to look for, and go from there. If you don't know what 262 shoots out of your rifle, then your chasing speeds that could / probably be wrong and you could be going way too hot. Reading to do a load of 26gr of Tac and getting speeds 2750 out of a 16" barrel is way over pressure and that will end up being more than a flattened primer issue. Mk262 does Not shoot that fast out of a 16" and is usually in the mid 2600's. Almost hitting a velocity of 2800 out of a 18" barrel with 77's is way too fast and is in dangerous pressure levels, but hey... It's not my gun nor will I ever be behind that type of load pulling the trigger.
Now I'm not trying to sound rude and I don't really care what people want to do with their loads but I just hope people do things right to avoid unneeded risk.
Who are you telling that too?
Whiskey&beer
11-01-14, 20:18
Hey Clemomsds - sorry but that wasn't directed at you in any way. You're doing damn fine on your loading / shooting so don't mind me! I read a post where I seen way heavy of loads so I made a comment. I'd just hate to hear someone do a load that could potentially get someone hurt.
Ramshots 5.56 data for the 77gr bullets show (20" barrel)
Bullet weight: 77 grain HP.
Start load: 22.1 grains (2525 – 2625 Ft/p/sec)
Maximum load: 24.5 grains (2750 – 2850 Ft/p/sec). <62000 Psi"
This is my mk262 recipe.
Brass: LC trimmed 1.750
Bullet: Nosler 77 gr Custom Competion
Primrs: CCI #41
COAL: 2.255 with a light crimp.
Powder: Ramshot TAC
23.0 gr. was the best accuracy. 1/8 moa was the best three shot group I was able to achive. 1/4 MOA was average.
23.5 gr. is my general purpose load for shooting 600 yrds. right about 2700 fps and 1/2 moa.
24.1 gr. I was able to achieve 2750 fps average
24.5 gr chronoed right at 2790-2800. But accuracy suffered and groups opened to 1 moa
24.8 gr is what I use for hog hunting. The nosler cc bullet has explosive results.
25.0 gr loads I started seeing pressure signs of flattening primers.
AR-15 has a 20" Shilen SS barrel 1/8 twist with 223 Wylde chamber.
http://i43.photobucket.com/albums/e400/rhino4x4/Guns/AR15side.jpg (http://s43.photobucket.com/user/rhino4x4/media/Guns/AR15side.jpg.html)
Best 3 shot group at 100 yrds
http://i43.photobucket.com/albums/e400/rhino4x4/Guns/BestARgroup.jpg (http://s43.photobucket.com/user/rhino4x4/media/Guns/BestARgroup.jpg.html)
Whiskey&beer
11-05-14, 14:55
Hey Ace - can you advise on type rifle, barrel type and length? It always helps on checking out loads so loaders know what others are using for comparison reasons.
I updated my post on page two, to make it a little more legible.
Alaska3006
01-08-15, 22:53
I believe Black Hill uses TAC in the MK 262 load.
24.7 grain with WIn Small Rifle primer in WCC cases.
I use 24.1of TAC in LC brass with CCI 41 primers all with 77 Gr Sierra with Cann
And a mild crimp using Lee Factory Crimp Die 2750 FPS
2.245" COAL
For me, velocity matters as much as accuracy, given my realistic accuracy expectations for the cartridge and carbine. In my case, I run a lot of DM Courses throughout the year, so we frequently take the 5.56 16" and 18" guns out to 600yds on steel, and the targets at the flat range are mostly 18" plates, with varying sized plates in the field ranges in the canyons. This is at North Springs Range in Utah, which is a $5.4 million range that is basically shooting heaven.
Anyway, especially in higher winds, it is difficult to hear the impact of even 77gr on steel once we get out to 450yds and farther. Guys that have shown up with Mk.262 boxed ammo have always had really good groups in the morning on Day 1, but most everyone brings top-end builds with Compass Lake, HCS, Krieger, Douglas Super Match, and barrels of that quality. After dry-firing during the fundamentals overview with coaching, a lot of guys will print a 1/2 MOA group first rounds out of the pipe with Mk.262, so I can attest to the fact that at least the loads I have seen have been exceptionally accurate.
The reality is that if you are shooting to 600yds, 1.5 MOA is an acceptable accuracy standard, although I of course prefer better. Your ability to dope the wind and hold a consistent position throughout play a much bigger factor in this for me.
As to powders, I personally have XBR, RL15, TAC, N530, AA2520, CFE, BL-C(2), etc. I lean towards speed for the reasons I stated. You just can't get enough from 5.56 case capacity when you start looking at impacting steel with authority past about 300yds.
I think the 77gr tipped SMK with .420 BC will be interesting, because that is closer to what the 75gr A-MAX is, which is a great bullet for the .223 Rem.
Either way, run the highest BC bullet that you can, as fast as you safely can. That's my basic approach to the 5.56/DM.
Where we shoot, on a bad day wind will make us hold 3-3.5 mils for wind at 1000 with the 77 smk. And at 500 we rarely have to hold very much off the edge of an IPSC sized target. Repeatability is more critical for me. But I definitely like to get the bullet over 2650 out of the barrel.
Alaska3006
01-12-15, 16:48
What length of barrel
I haven't shot them yet because my MK12 SPR is currently getting Cerakoted, as soon as temps get back up above freezing and the gun is back together I have two boxes of the new BH 77gr. TMK I'm going to test. Just punching the data into my ballistic calculator it shows they stay super sonic out past 1000 yards (depending on weather conditions). And yes the BC is .420, the round itself is over an inch long unlike the 77gr OTM which is under an inch. (.996 vs 1.07) not much but it counts.
The BH 77gr OTM shoot an average 2740 FPS out of my 18" barrel, so I'm guessing the others will be very close. The temp was 80 dagrees with humidity almost matching the temp.
Sparky5019
03-12-15, 20:25
Anyone tested Accurate 2230 for the MK262 Mod 1? They list a load that posts reasonable velocity and pressure specs. Just curious if y'all have tried it?
I have not, my testing with 8208 yielded the results I was looking for so I stopped there. 23.1 grains gave me 2740FPS @ 80 degrees with good down range performance closely matching that of black hills MK262 mod 1.
BHA MK262 mod 1 gives me 3.907" groups @500 yards and my reloads give me similar performance.
An update for my previous post on the new tipped match king rounds from BHA, my adjustment for the OTM was 12 moa @500 yards while the TMK only needed 11 moa @500 yards (100 yard zero). Fantastic down range performance for factory ammo.32105
I believe Black Hill uses TAC in the MK 262 load.
24.7 grain with WIn Small Rifle primer in WCC cases.
I use 24.1of TAC in LC brass with CCI 41 primers all with 77 Gr Sierra with Cann
And a mild crimp using Lee Factory Crimp Die 2750 FPS
2.245" COAL
I have finalized my Mk262 Mod1 duplicate load and concur with these numbers.
LC'11 virgin brass
Ramshot TAC (around 24.0 and again around 24.8gr for 2 accuracy nodes)
FGMM primers
77SMK
2.245"
LFCD
trim to 1.750"
headspace 1.460"
Rifle: AR15 with DD CHF S2W 18" 1/7 Nitrided barrel - but shoots great in other AR15 barrels too.
24.8gr is the load that I chose because of higher velocity. It'll hit 2850ish in the summer from the 18" barrel. I do see large velocity swings in summer vs. winter, but accuracy seems great regardless.
Rifle: AR15 with DD CHF S2W 18" 1/7 Nitrided barrel - but shoots great in other AR15 barrels too.
24.8gr is the load that I chose because of higher velocity. It'll hit 2850ish in the summer from the 18" barrel. I do see large velocity swings in summer vs. winter, but accuracy seems great regardless.
Man that would be way out of my comfort zone... How many times can you load your brass?
Sparky5019
03-13-15, 08:53
I have finalized my Mk262 Mod1 duplicate load and concur with these numbers.
LC'11 virgin brass
Ramshot TAC (around 24.0 and again around 24.8gr for 2 accuracy nodes)
FGMM primers
77SMK
2.245"
LFCD
trim to 1.750"
headspace 1.460"
Rifle: AR15 with DD CHF S2W 18" 1/7 Nitrided barrel - but shoots great in other AR15 barrels too.
24.8gr is the load that I chose because of higher velocity. It'll hit 2850ish in the summer from the 18" barrel. I do see large velocity swings in summer vs. winter, but accuracy seems great regardless.
With those seasonal velocity swings, do you get pressure signs?
With those seasonal velocity swings, do you get pressure signs?
I developed the load in the summer at 90* or so and there were light ejector wipes on some brass like all 5.56 pressure ammo in my experience, but nothing excessive.
Man that would be way out of my comfort zone... How many times can you load your brass?
Good question. How many times can you reload LC brass at 5.56 pressure?
Good question. How many times can you reload LC brass at 5.56 pressure?
Typically until the primer pockets won't hold a primer any more. At those pressures, I doubt you will get that many loads... 77gr SMK's @ 2,850fps from an 18" barrel is smokin! Mk262 is 2,750 from a 20" barrel and they are loaded to a fairly high 5.56 pressure.
FWIW, I can get 8-10 loads out of LC brass before the primer pocket is toast.
Typically until the primer pockets won't hold a primer any more. At those pressures, I doubt you will get that many loads... 77gr SMK's @ 2,850fps from an 18" barrel is smokin! Mk262 is 2,750 from a 20" barrel and they are loaded to a fairly high 5.56 pressure.
FWIW, I can get 8-10 loads out of LC brass before the primer pocket is toast.
I checked my data and you are right. At 55* MV was 2701 from 18" DD barrel. The 2850 number stuck in my head from when I was working on the 75HPBT, not the 77SMK.
I do not have hot weather chronograph numbers for TAC and the 77SMK. but I shot the first OCW in the summer at 90*+ and went up to 24.9 with some ejector swipe. QL predicts 2756 @ 90* based on 2701 @ 55*.
32116
Sparky5019
03-14-15, 13:06
I developed the load in the summer at 90* or so and there were light ejector wipes on some brass like all 5.56 pressure ammo in my experience, but nothing excessive.
Good to know. Thanks!
I use TAC with the 77s (Nosler & Sierra), cause it's what I have.
I get 2,735 fps out of a Noveske 18" SPR barrel with the 77 Grain Noslers using 24.2 TAC and Rem 7 1/2s. This is as hot as I care to go - brass marks look similar to IMI M193 (bright spots on case head, but no (or very minor) ejector marks. Brass is factory new LC, and I stop at 4 loads total. Accuracy is about MOA, which matches the shooters ability (more or less).
The IMI Razor 77 gr loads in the same rifle run 2,768 fps and case marks are somewhat more pronounced.
Skyfire1201
02-22-16, 23:10
I've had good results with the following:
- LC NATO brass
- Rem 7 1/2 primer
- SMK 77gr w/ cannelure
- 24.1gr of RL-15
Our of my Noveske 18" SPR barrel, I'm getting comparable velocity to Blackhill commercial Mk262, without any over pressure signs. Avg velocity is 2646 (vs 2637 from the BH), SD of 16, in conditions of 66F, 54% humidity and 274ft elevation.
The only thing I'm puzzling about is temperature stability. The Blackhill Mk262 produced avg velocity of 2724 on a 71F degree day. Does factory Mk262 supposed to be this temperature sensitive?
I've had good results with the following:
- LC NATO brass
- Rem 7 1/2 primer
- SMK 77gr w/ cannelure
- 24.1gr of RL-15
Our of my Noveske 18" SPR barrel, I'm getting comparable velocity to Blackhill commercial Mk262, without any over pressure signs. Avg velocity is 2646 (vs 2637 from the BH), SD of 16, in conditions of 66F, 54% humidity and 274ft elevation.
The only thing I'm puzzling about is temperature stability. The Blackhill Mk262 produced avg velocity of 2724 on a 71F degree day. Does factory Mk262 supposed to be this temperature sensitive?
My understanding is that MK262 isn't supposed to be, but I honestly haven't tested the factory ammo in large temperature shifts. Thanks for the data, I haven't used RL-15.
Let me know if you test the temprature stability of that load.
RL15 is considered to not be particularly temperature stable.
RL15 is considered to not be particularly temperature stable.
It's horrendous. Like TWICE the velocity swings at half the temp change when compare to IMR 4064
I've refined my load. Mk262 clone is 24.8gr TAC, LC 1x brass, 77SMK or 77CC, CCI 41, LFCD in cannelure. This load is 5.56 pressure. My DD 18" 5.56 will tolerate it but the Krieger 20" .223 Wylde will pop primers, especially in the heat. Many others report same Mk262 clone at 24.7 or 24.8gr TAC.
24.0 is on the node for 20" barrel and is .233 pressure.
23.5gr H4895 and a CCI450 pushes 75gr Hornady OTMs at 2650 from a 16" AR.
I think the Sierra 77s have a different ogive so it might be higher pressure, maybe work up with H4895 to see if it gets you where you want.
So in my free time I have been working up loads using the 77gr SMK, the 77gr Nosler, and the 75gr Hornady match bullets.I have had good luck with Hornady bullets in the past so I am favoring them in this project. I started loading these in October of last year. I used Hodgdon's CFE and BLC2 powders and Accurate Arms 2460 and 2230C (a canister powder I got from a show I was working, no longer made). My friend was going to let me borrow his chronograph. So I finally got to chrono some loads! I got tired of waiting and bought me a chrono. I used my 26 inch Savage 12 FV and my 16 inch PSA AR15 for testing. From everything I gathered, 2650 from a 16 inch barrel is what the MK 262 load should shoot. I have seen one source that said 2750, but I don't think that is possible with commercial powders. So I used CFE, BLC2, AA2460, AA2230C. I used the 75gr Hornady Match bullet. I also used the 69 SMK bullet...I was testing the difference between the 2460 and the 2230C powder (Accurate said use 2460 data for both as they are the same). I had some 77 Nosler loads, but ran out of time. Using the 75 gr Hornady bullet, the 2460 shot 2690 fps out of the 16 inch barrel with 20 shots; 2950 fps out of the Savage 26 inch barrel. BLC2 shot 2620 fps and 2800 fps. The CFE was a surprise coming in at 2768 fps and 2992 fps! The 2230C and 2460 was so close as to be identical across the different bullet weights. All the loads showed no high pressure signs in either gun. No loads were max loads. Except the CFE load is lower in the Hodgdon manual than in the Hornady manual...I went with the bullet maker's load. So in my eyes, the MK262 load is not unobtainable by mortals! Now, to see how accurate they are!
23.2 XBR with the 77 SMK is max in the Hodgdon manual.
23.2 XBR with the 77 SMK is max in the Hodgdon manual.
At 223 spec. Isn't the mk262 a higher 5.56 pressure and outside of SAMI
At 223 spec. Isn't the mk262 a higher 5.56 pressure and outside of SAMI
That was according to Hodgdon which is a 223 listing. There is no 5.56 in the Hodgdon data. You have to look for Hornady 5.56 Service Rifle data. Accurate Arms/Western Powders also has 5.56 pressure data. Many are using TAC for MK262 loads and are getting pressure signs. I have used 2460 with good results. I think Sierra also has 5.56 data. All the other manuals will only give you 223.
After reading this entire thread, I thought it worth mentioning. Black hills adds a flash retarder into their MK262 M1 load which likely explains the charge weight being higher than expected.
Jimbeaux82
06-06-16, 04:31
I too have been working up a 77 gr load using AA 2460. I am working up for a 20" barrel AR. How are your groups looking and now that you have a chrono, what velocity seems to be most accurate?
30 cal slut
08-08-16, 10:01
Just thought I'd chime in here and post a pic.
I stumbled on some ammo that I reloaded a few years ago and totally forgot about. I was totally stoked because I thought I was out of ammo and have been really lazy cranking out rounds.
Anyhoo, the box was labeled "Mk262 clones." But like an idiot I forgot to list the important stuff like powder charge, etc. I do remember that I was using 8208 XBR, CCI #41 primers, and Sierra 77 gr OTM bullets. I have the powder charge written down ... somewhere.
Took my Mk12 build (Centurion Arms upper) to the range and poked holes at 100 yards from the prone.
I stored the rifle with the scope pulled off, so my goal for the day was to re-zero the optic.
And this is what I got on the first string.
5 shot group.
The flyer in the 10-ring was me trying to stifle a fart as my range buddies were downwind of me. It's hard to steady the reticle when you have to fart.
This ammo was an attempt to duplicate factory Black Hills Mk262. I didn't quite get there as I recall having to adjust elevation down by 1.6 MOA, but windage was spot on.
http://i1058.photobucket.com/albums/t409/training_ne/Mobile%20Uploads/image_5.jpeg
My God! Some of the loads and velocities you guys are using are borderline insane, even for 5.56!
Mk262 only spec's out at between 2700-2750 at the muzzle from a 20" 1X7 M16A2 barrel. Some of y'all must be dabbling in the Black Arts to get 2750-2800 out of a carbine barrel.
Mk262 only spec's out at between 2700-2750 at the muzzle from a 20" 1X7 M16A2 barrel.
I think it's spec'd for an 18" SPR barrel. Mk262 runs much hotter that 2750 out of our 20" barrel.
colt191145lover
08-31-16, 14:17
Black hills Mk 262 mod 1 factory seconds (white box) averaged 2798 FPS out of my 18 inch BCM barreled SPR . IMI razor core 77 gr was 2830 FPS ,both shot over a magnetospeed.
My Razor Core 77 gr runs 2,778 fps out of an 18" Noveske SPR barrel (PACT chronograph), and 2,734 fps out of a 16" barrel (Noveske N4 Light) - just noting for comparison.
IIRC, the Black Hills Red Box Mk262 ran slightly hotter, but I don't have those numbers anymore.
colt191145lover
08-31-16, 17:45
My Razor Core 77 gr runs 2,778 fps out of an 18" Noveske SPR barrel (PACT chronograph), and 2,734 fps out of a 16" barrel (Noveske N4 Light) - just noting for comparison.
IIRC, the Black Hills Red Box Mk262 ran slightly hotter, but I don't have those numbers anymore.
Thanks for the info , I dident get a chance to run any through a 16 inch barrel . Hopefully soon
More reference data from a recent range trip with my BCM 16" SS 1/8 twist. OAT was 69 degrees F
Name: BCM 16 SS w CBC Mk262
Notes: CBC Mk262 OTM 77gr
Number of Shots 10
Extreme Spread 72
Average 2712
Standard Deviation 21
Name: BCM 16 SS with IMI Mk262 Mod 1
Notes:
Number of Shots 10
Extreme Spread 54
Average 2689
Standard Deviation 18
This was using the Competition Electronics ProChrono Digital chronograph.
chamber143
09-05-16, 18:30
I only have varget to play with right now but i was getting 2650 under 24 grains of varget which is max. I didnt like the groups so i bqcked off to 23.1 gr and i like it better. Getting 2525 fps with this. I saw pressure signs with some of the BH mk 262. Varget gives me some pressure signs at 23.4 grains.
I only have varget to play with right now but i was getting 2650 under 24 grains of varget which is max. I didnt like the groups so i bqcked off to 23.1 gr and i like it better. Getting 2525 fps with this. I saw pressure signs with some of the BH mk 262. Varget gives me some pressure signs at 23.4 grains.
What barrel length? IIRC, I used 24gr Varget under 77gr SMK's that averaged 2,700fps from an 18" barrel with excellent accuracy.
chamber143
09-06-16, 14:58
What barrel length? IIRC, I used 24gr Varget under 77gr SMK's that averaged 2,700fps from an 18" barrel with excellent accuracy.
16 inch
colt191145lover
09-11-16, 13:50
Got some more data.
16 inch BCM ELW shooting IMI Razor core 77g over a magnetospeed.
4 shots
Avarage 2675 fps
High, 2695 fps
Low, 2649 fps
S.D. 21.2
Lots of good info in this thread! Currently waiting on a good day to get out and test some mk262 clones myself using xbr and tac. I have not shot any black hills mk262 but I have shot a ton of IMI Razor core 77 and have had really good results so that's what I will be comparing my hand loads to.
Some results I've seen from the IMI 77:
10 shot velocity avg was 2828 with a SD of 13 (20" barrel, 65 degrees)
Shooting 10 shot groups I've had Mean Radius numbers from .37 to .50 with the average probably falling around .43
45063
The IMI 77 is pretty good stuff for the money 73 cents/round buying in bulk, but I'm hoping to get slightly better accuracy out of my hand loads for 30 or so cents less per round!
DD lower with SSA trigger
Aero precision upper with 20" Larue stealth barrel
Currently waiting on a good day to get out and test some mk262 clones myself using xbr and tac.
Forget XBR if velocity match is what you're after. I use it and load it pretty hot, but can't match Black Hills performance without getting blown primers and stuff.
Series 5 Shots: 10 NV20 75°F
Min 2755 Max 2807 BH
Avg 2782 S-D 15.6 MK262
ES 52
Series Shot Speed
5 1 2784 ft/s
5 2 2776 ft/s
5 3 2807 ft/s
5 4 2792 ft/s
5 5 2786 ft/s
5 6 2798 ft/s
5 7 2761 ft/s
5 8 2780 ft/s
5 9 2783 ft/s
5 10 2755 ft/s
I've bumped mine to 24.4 TAC Nosler 77 gr OTM 2.245 LC 41
Series 2 Shots: 10 CC77OTM 75°F
Min 2751 Max 2806 24.4 TAC
Avg 2771 S-D 17.6
ES 55
Series Shot Speed
2 1 2753 ft/s
2 2 2769 ft/s
2 3 2760 ft/s
2 4 2769 ft/s
2 5 2806 ft/s
2 6 2767 ft/s
2 7 2768 ft/s
2 8 2751 ft/s
2 9 2797 ft/s
2 10 2777 ft/s
+00.0 95 24.40 2771 1313 59647 8765 97.1 0.987 ! Near Maximum !
What's the mk262 clone load that I believe Mark developed that is working well for everyone on here?
Assuming it's a .223 load of course.
What's the mk262 clone load that I believe Mark developed that is working well for everyone on here?
Assuming it's a .223 load of course.
If you mean my load, it's 23.4 gr XBR. That's over max, and powder lot dependent. Work up to it. Again... TAC is likely the better choice if you're after velocity.
Here are a couple that I use; I'm chasing velocity a little bit as I like to shoot steel with it at 600-800 yards:
All shot in an 18" suppressed Douglas Barrel
77gr Nosler CC @ 2.25 in WIN NT Brass
Tula KVB556M Primer
23.4gr IMR 8208XBR
2680 FPS AV
13 SD
77gr Nosler @ 2.25, WIN NT Brass
Tula KVB556M Primer
24.3gr TAC
2767 FPS AV
9 SD
Accuracy is about the same. Like the TAC load better for the speed and that it is forgiving pressure-wise. I've never done this with 8208, but that same TAC load with a hot chamber and ammunition that had been sitting in direct sun in a clear box for hours on a summer day, got 2790 AV. The rounds were hot to the touch even before going in the rifle. Ejector swipes but no flattened, pierced, or blown primers.
Also have some 2000mr load data but would have to dig it up. IIRC it took heavy, compressed charges but got some incredible velocities with no pressure signs.
If loading with TMKs, I back charges off .2gr.
Here are a couple that I use; I'm chasing velocity a little bit as I like to shoot steel with it at 600-800 yards:
All shot in an 18" suppressed Douglas Barrel
We shoot a .223 pressure 77gr load out to 1000 all the time. Accuracy and low S.D. took priority for us. Now if you're in a really windy spot... every bit of speed is helpful. Our spot is usually mild winds.
MisterHelix
10-20-17, 10:43
The load I use for 77 grain projectiles is listed in the Hodgdon reloading data as "MAX" for .223. With this powder/charge in a 5.56 chamber I see no significant pressure signs.
The velocities listed are from a 16" barrel. From a 12.5" barrel it goes about 2,400fps.
So, not a MK262 "clone", but decent velocities for a .223 pressure load, and pretty low SD.
Nosler 77 grain CC
Hodgdon Benchmark @ 22.8 grains
CCI 450 (small rifle magnum)
LC brass
Ballistic Coefficient: 0.340
Bullet Weight(gr): 77.00
# FPS
4 2549
3 2559
2 2563
1 2557
Average: 2557.0 FPS
SD: 5.9 FPS
Min: 2549 FPS
Max: 2563 FPS
Spread: 14 FPS
True MV: 2566 FPS
gunnerblue
10-20-17, 11:16
I shot this 10-round group yesterday out of my precision build with a 16” BCM 410SS barrel:
77 gr SMK
23.5 gr IMR 8208 XBR
LC once-fired brass (no prep)
Federal 205M
Redding Type-S FL die with 0.245 bushing
Forster Benchrest seater
Velocity ~2675
ES 30
SD 11
I’m not really concerned with ES anymore, but would love to find some Russian primers and see if I can tighten up the SD and group size.
We shoot a .223 pressure 77gr load out to 1000 all the time. Accuracy and low S.D. took priority for us. Now if you're in a really windy spot... every bit of speed is helpful. Our spot is usually mild winds.
Probably a good point. If I'd had the rifle two weekends ago, wind holds would have been 2 - 3.5 mils with the faster TAC load at 1000 depending on gusting. It varies several times over the distance due to the terrain, and I am not yet good enough at reading it to be confident at that distance unless it is an exceptional weather day...probably need all the help I can get!
Here are a couple that I use; I'm chasing velocity a little bit as I like to shoot steel with it at 600-800 yards:
All shot in an 18" suppressed Douglas Barrel
77gr Nosler CC @ 2.25 in WIN NT Brass
Tula KVB556M Primer
23.4gr IMR 8208XBR
2680 FPS AV
13 SD
77gr Nosler @ 2.25, WIN NT Brass
Tula KVB556M Primer
24.3gr TAC
2767 FPS AV
9 SD
Accuracy is about the same. Like the TAC load better for the speed and that it is forgiving pressure-wise. I've never done this with 8208, but that same TAC load with a hot chamber and ammunition that had been sitting in direct sun in a clear box for hours on a summer day, got 2790 AV. The rounds were hot to the touch even before going in the rifle. Ejector swipes but no flattened, pierced, or blown primers.
Also have some 2000mr load data but would have to dig it up. IIRC it took heavy, compressed charges but got some incredible velocities with no pressure signs.
If loading with TMKs, I back charges off .2gr.
I have also used 2000 MR - it is a very energy dense powder and capable of generating incredible velocities. This is the one powder I have compressed and loaded to max and beyond with no issues. The charge weights per bullet weight are seem so high to be a typo. No doubt for sheer velocity I believe it has the possibility to exceed all others in both 223 and 308...
TAC generally increases about 2fps/°F. Most time people leave out any temp data which is relevant trying to clone. My post lists BH mk262 but is technically BH 5.56 77gr OTM fired from a Noveske match mod 0 20" medium varmint.
I have also used 2000 MR - it is a very energy dense powder and capable of generating incredible velocities. This is the one powder I have compressed and loaded to max and beyond with no issues. The charge weights per bullet weight are seem so high to be a typo. No doubt for sheer velocity I believe it has the possibility to exceed all others in both 223 and 308...
I primarily use this in .308 bolt action loads as it generates a lot of gas volume...fine in 5.56 but induced reliability problems with hotter loads in heavier-gassed large frames.
TAC generally increases about 2fps/°F. Most time people leave out any temp data which is relevant trying to clone. My post lists BH mk262 but is technically BH 5.56 77gr OTM fired from a Noveske match mod 0 20" medium varmint.
I've had better luck with it....closer to 1 FPS per degree in my use but I am going by ambient air temperature and do not have the capacity to measure actual case or chamber temp. Other ball powders and some extruded have been 2fps or more, but TAC has been pretty good.
Mostly my point was regarding measured velocity of BH 5.56 77 OTM or MK262 at what temp and barrel length for baseline. I have measured data that shows 30fps difference between 69°F and 85°F. At these pressure levels 30fps = .4gr TAC. I could probably up mine .1 to 24.5 but at 59k psi I'm losing safety margin.
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