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Thread: MK262 mod 1 load data help

  1. #91
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    Quote Originally Posted by markm View Post
    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!

  2. #92
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    Quote Originally Posted by mgrs View Post
    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...

  3. #93
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    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.
    Last edited by LMT/556; 10-21-17 at 08:59.

  4. #94
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    Quote Originally Posted by mic2377 View Post
    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.


    Quote Originally Posted by LMT/556 View Post
    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.

  5. #95
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    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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