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5.56mm Mk 262 Mod 0 or Mod 1 Handload Eq?

leeblackmanleeblackman Member Posts: 5,303 ✭✭
edited July 2008 in Ask the Experts
Anyone have an equivlant load for the 77gr Sierra Matchking at a muzzle velocity of 2,783 fps out of an 18" barrel?

I was think Accurate 2520 at about 32grs????

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    rufe-snowrufe-snow Member Posts: 18,650 ✭✭✭
    edited November -1
    If it's a load with Accurate Arms powder, I would try their web site first. Last time I was on it, they had very extensive loading data.

    Try the GB handloading forum if you don't have any luck with the AA site. They had a very extensive list of handloading links last time I was on the forum. Your bound to find some .223 heavy bullet loads, can't guarantee they would be for AA 2520 though.
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    nononsensenononsense Member Posts: 10,928 ✭✭✭✭
    edited November -1
    leeblackman,

    Do we assume that you're using an AR15/M16 platform?

    I would be a little wary of a 32 grain load of AA-2520 since the case usually only holds a tad less than 31 grains in total. You might be able to vibrate enough of this powder into the case to allow you to seat the bullet but pressures will be on the catastrophic side. Maybe you mean 23 grains(?), which is a lower starting range for pressure but doesn't quite make it to your velocity requirement obviously.

    I have used AA-XMR-2495 with good results when testing loads using these heavier bullets. This powder will get you close to your velocity without the attendant pressure problems.

    Best.
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    leeblackmanleeblackman Member Posts: 5,303 ✭✭
    edited November -1
    Ooops, yes, big mistake.... Ment 23grs, NOT 32grs....


    Another thing I was looking at was maybe using 24.1 grs of Reloader 15 or 23.9 grs of Varget.
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    nononsensenononsense Member Posts: 10,928 ✭✭✭✭
    edited November -1
    leeblackman,

    "Ment 23grs, NOT 32grs...."

    That's good, I feel better.

    With an 18" barrel, you might find it a little harder to achieve your velocity goal but you won't know until you try some testing. My hot loads are a touch below your desired maximum.

    Both of your other choices, Re-15 and Varget, will work but they might leave some additional fouling since not all of the powder will get burned in that short barrel. I would prefer to see you go with the AA-2520 before these other two. Better selections would be:

    AA-XMR-2495

    V V N-135

    IMR-3031

    Load some tests and go shoot a ladder to see where your barrel wants to shoot round groups.

    Best.
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    leeblackmanleeblackman Member Posts: 5,303 ✭✭
    edited November -1
    The whole inspiration behind this, I ran across an article over the M16 Mk 12 Mod 0 rifle using the Mk 262 Mod 1 cartridge getting hit capability on targets at 1000 meters. Literally they showed groups on a target shot from 1000, what I remember being under 14 inches. I don't remember the magazine, or the exact details of the article, as I didn't buy it from the bookstore. I wish i would have. But when I looked up the Mk 12 Mod 0, it only has an 18" precision barrel with a unique muzzle break that makes it about 20 inches.

    I could be wrong though, maybe it wasn't the navy mk 12 mod 0, but maybe it was the marine or army designated marskmans rifle... I can't remember.

    i just really want to duplicate the Mk 262 Mod 0 or Mod 1 cartridge specs that I found on wikipedia and want a powder charge equivlant.
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    quickmajikquickmajik Member Posts: 16,324
    edited November -1
    I know a guy that has a regulated gas tube on his AR sniper setup. He can adjust the gas to his load of choice and what not. It has got a low profile gas block. Sweet little set up, its got a 18" spr barrel on it with a full length gas system. And a Larue rifle length handguard, I cant recall all the details but I think he had to modify the handguard some so it would fit and he could adjust it.

    He uses the 77grain load in his rifle and he seems to like his rifle more then his girlfriend.
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    nononsensenononsense Member Posts: 10,928 ✭✭✭✭
    edited November -1
    leeblackman,

    "Barrel: An 18-inch (457 mm) threaded-muzzle match-grade free floating stainless steel heavy barrel with a 1:7 (178 mm) rifling twist ratio is standard for the SPR. The barrels are manufactured by Douglas Barrel with a special contour to maximize accuracy and to minimize weight. An OPS Inc. muzzle brake and collar (to align the OPS Inc. 12th Model Suppressor) is installed with the barrel. These barrels were designed to take advantage of the new Mk 262 cartridge, which uses a 77-grain (5 g) bullet."

    "Optics: Due to the relative modularity of the system, optics (as well as almost everything else) can be mounted according to the operator's wishes. However, SPRs are most often seen with a 3.5-10x40 mm Leupold LR M3 (SPR/A), a 2.5-9x36 mm TS-30 (SPR/B), or a 3-9x36 mm TS-30 A2 (Mk 12 Mod 0/1) Mid Range/Tactical Illuminated Reticle Dayscope (civilian versions are known as the Leupold Mark 4 MR/T 3-9x36). Night vision devices can also be attached. These scopes usually come with flip open dust covers and a honeycomb anti-glare anti-reflection device (ARD). Given Nightforce Optics' recent NAVSPECWAR contract, it is believed that many NAVSPECWAR issued SPRs will use the Nightforce 2.5-10x24 NXS scope."

    I guess my first comment would have to be that Black Hills Ammunition is manufacturing this load and it's marketed as the Blue Box. So you should be able to buy it if nothing else.

    77 Gr. Sierra MatchKing (also Available in Molycoat)
    Velocity 2750 FPS
    Energy 1293 Ft. Lbs.

    Many of us have already shot .223 Rem. loaded with 77 and 80 gr. bullets at the 1,000 yard line with groups smaller than the 14" quoted in the article. Of course most of us use longer barrels than 18" and our sights and scopes are probably significantly better than what the military provides for combat.

    My second point is that this version (Mk 262 Mod 1) is loaded to higher than normal pressure specifications which is how they get that velocity. As an aside, the Mod. 0 was loaded with bullets lacking a cannelure while the Mod. 1 bullets have a cannelure. The cannelure was added when the military discovered problems with bullet set back.

    Since all barrels and all rifles are different, I would start with the components that you already know and begin a load development program the same as you would when you want to work with any cartridge. This way you'll know what works for your rifle. Any of us could give you the powder information from our loads but the chance that they would work accurately for you are slim. That's why I listed 3 powders but no loads, you have to do this work.

    Last but not least, if you find that the Sierra MK don't shoot as accurately as you'd like, look at the new Berger Match BT (non-VLD):

    22 cal 77 gr Match BT 0.224 0.389BC 1:8" 224077T

    Best.
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    quickmajikquickmajik Member Posts: 16,324
    edited November -1
    I always reccomend the Ops. inc. R3E2C muzzle break when the AR-15/AR-10 comes up. It does not have the QC sound supressor attachment collar but it works well on those rifles that need a muzzle break without the dust signature that most brakes cause. The R3E2C will still cause some dust disturbance, that cant be helped without a big surpressor, then you still see dust-up. But it is still one of the most effective brakes in its class that I know of.

    If you need a brake for your rifle and need it to be discreet as posible the R3E2C is the way to go. it will cause some uncomfortable blast to the guy at your 3 o'clock and 9 o'clock believe me, But its one of the best. I don't know of a better one. Thats i have one with the firts chamber hole drilled out to .25 cal. screwed on my 20" DMR clone. If anyone knows a better discreet brake my money is on nononesense.

    I know from shooting alot of 75 grain match loads that the recoil impulse is noticeably more. especially in shorter gas tube lengths. Quick shooting is no problem with my rifle I never loose sight picture during quick strings.
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    leeblackmanleeblackman Member Posts: 5,303 ✭✭
    edited November -1
    I found a whole bunch of the Sierra 77gr Matchking with channellure from Wideners. I found very consitant Lapua brand brass in 5.56mm Nato, all I need is a primer and powder combination and to figure out a way to crimp the primers into the pocket....
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