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Non Barrier blind ammo velocities out of a 10.5"

Discussion in 'NFA Firearms and Accessories' started by gotigers, Oct 4, 2013.

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  1. gotigers

    gotigers Member

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    I recently got the stamp for my SBR. I want to run the most efficient ammo through it. I have been researching for months, but it is hard to find velocity data from a 10.5" barrel. So, I ran a few rounds through a chrono. I wanted to find an open tip, non-barrier blind ammo for home defense. I want one with a velocity over 2300 FPS. Edit: Other criteria were figured out months ago.

    This is not a scientific test. I only ran ammo that is NOT barrier blind. I might run some barrier blind later. I ran some XM193 and AE223 55fmj to give me a reference that I am familiar with. I sighted in at 100 yards with the Federal XM193 and ran 2-5 shot groups of AE223J for a confirmation of sorts. Then I ran 2-5 shot groups at 100 yards of all I had. Edit: A small sample size. As I said this is not a scientific test. I ran it to record the data. I figured I would share it.

    It was no surprise the Black Hills MK262 and the Hornady TAP 75gr T2 retained most of their published velocities. The MK262 had better groups.

    The best groups were from the Hornady Steel Match, but all ammo had acceptable groups.

    The PPU performed very well. Considering the low price, this is a serious contender.

    The Hornady Match 75gr BTHP and the Fiocchi 77gr SMK had velocities below the 2300 fps requirement, so I stopped with one 5 shot group.

    Weather:
    Sunny to partly cloudy
    80 degrees
    60-80% humidity
    Breeze. 5-10 mph, at my back

    Set up:
    10.5" FN chrome lined barrel, 1:7 twist, 5.56 NATO chamber
    CMT-TAC upper/lower
    Young Mfg BCG
    YHM QD Brake
    ALG Defense QMS with yellow JP Springs. Breaks at 4.5lb.
    Spikes ST-T2 buffer
    Nikon P223 4-12x40 BDC 600
    Pro Chrono at 10 feet

    table_zps7cdc9bfc.jpg


    setup1_zps3a3c8224.jpg
    setup2_zpsdcaf697b.jpg


    I am to lazy to post all the pics of the groups, but you can see the 5 shot groups in this photobucket album:
    Pics of groups

    Some of the groups shot very low. Sometime during the TAP groups, I must have moved the zero. I re-zero'd between the PPU groups.
    allgroups_zpsdc572b75.jpg

    edit: Corrected XM193 BC.
     
    Last edited: Oct 5, 2013
  2. Jim K

    Jim K Member.

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    So published velocity figures based on a 20+" barrel are higher than those with a 10.5" barrel. The testing effort and data presentation are excellent and appreciated, but the results are not really news.

    FWIW, the old rule of thumb, about 50 fps per inch loss/gain, seems to hold up.

    Jim
     
  3. rcmodel

    rcmodel Member in memoriam

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    After 50+ years of shooting, military service, gun collecting, gunsmithing, reloading, bullet casting, hunting, and general all-around gun foolishness that has cost me way too much money, time, and hearing.

    I have no idea what you are talking about!

    Could you explain further what 'barrier blind' is referring too?

    Thank you!

    rc
     
  4. gotigers

    gotigers Member

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    To Jim K: We all know velocities are slower from shorter barrels. I wanted to have a warm and fuzzy for the ammo I select for my first SBR. I figured i'd share. However, some cartridges performed much better with retained velocities per penny.

    To rcmodel: Barrier blind bullets will penetrate barriers easier, such as sheetrock, glass, body armor, etc. Usually bonded jacketed bullets, solid core, solid base, all copper and penetrators are considered barrier blind. Gold Dots, Bear Claws, TSX, MK318 and M855 are some barrier blind cartridges.

    God forbid I ever need to use this SBR in defense, I want a bullet that is not barrier blind so there will be less of a chance of wall penetration in the house. The non bonded OTM's, non bonded jacketed hollow points and varmint bullets are usually not barrier blind. The heavier OTMs will penetrate heavy clothing and have great terminal ballistics, but should penetrate less through barriers.
     
  5. RyanM

    RyanM Member

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    Have you tried shooting that thing without hearing protection? Doing so may just change your mind about using it for home defense.

    Following a self defense shooting, you may just need to hear bad guy #2 sneaking up behind you, or the cops yelling at you to drop the gun.

    There's a reason why military/SWAT often willingly downgrade all the way to 9mm, when they need a gun with a 10" or shorter barrel.
     
  6. gotigers

    gotigers Member

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    Edit: All guns are loud and can damage your hearing. I have a suppressor on the way, but even with a can it will cause hearing damage. The can I ordered, warranties a 10.5" and the ammo I selected is also covered. I researched this a year ago. It is presumptuous to assume otherwise. This gun is more for fun than anything. I doubt I will ever need it for anything other than punching paper. It is fun to shoot, record and try to learn from the data. Hopefully, someone else can use the data.
     
    Last edited: Oct 5, 2013
  7. RyanM

    RyanM Member

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    No, there's a difference between loud and LOUD. A 10.5" AR WILL damage your hearing in ways that a 14.5" will not.

    If you're suppressing it, you'll need to pick ammo that stabilizes 100% at the velocities you're getting. You should probably ask your suppressor manufacturer for a list of ammo that won't void your warranty. Some manufs won't warranty suppressors on SBRs at all.

    You really need to use more criteria than 2300 fps and not being "barrier blind."
     
  8. gotigers

    gotigers Member

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    Please, stay on topic.
     
    Last edited: Oct 5, 2013
  9. Jim K

    Jim K Member.

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    "Barrier blind" bullets (i.e., bullets that don't "see" barriers but just penetrate them) are just another version of the old metal penetrating idea. Nothing magic, just a harder bullet like the old bronze handgun bullets of the 1930's. They still depend on mechanical penetration, not on a heat dump as do true "armor piercing" bullets.

    Jim
     
  10. gotigers

    gotigers Member

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