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AR-15 ammo question

Discussion in 'Black Rifle Forum' started by Petrie, Jan 26, 2010.


  1. Petrie

    Petrie
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    I have a DPMS AR chambered in 5.56 x 45 mm. Can I shoot any .223 I want out of it? I've only shot 55 gr so far. Can I run 70-80 out of it with no trouble? Are the heavier bullets longer? Will they jam into the rifling? Are the heavier bullets too long to fit in a magazine? I only have a 1/9 twist so I don't know that my gun could handle the heavier bullets anyway.
     

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  2. Glock2008

    Glock2008
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    You can use any .223 rem ammo, but some of the heavier bullets are going to be inacurrate with a 1:9 twist and may not fit in your magazine. bullets in the 50-70 grain range are going to be your best bet for a 1:9 bbl.
     

  3. deadmonkey90

    deadmonkey90
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    Thanks, educational for me as well. I was planning on shooting 55gr 5.56 in my 18in bbl with a 1:8 twist
     
  4. lawman800

    lawman800
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    Juris Glocktor

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    I read 55 grain for 1 in 7 and 62 grain for 1 in 9.
     
  5. mboylan

    mboylan
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    1:7 will stabalize the heavier 68 and 75 grain bullets. 1:9 will work for 55 and 62 grain bullets. I would not try 78 grain match bullets out of a 1:9 barrel. You would be wasting your money.
     
  6. pcar

    pcar
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    What happens with 55 grain in a 1:7?
     
  7. KalashniKEV

    KalashniKEV
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    Flip that and you'd have the optimal stabilizations:

    1/7- 62 grain- M855
    1/9- 55 grain- M193

    Mk. 262 Mod 1 is 77 grain, and wouldn't stabilize well from a 1/9.
     
  8. deadmonkey90

    deadmonkey90
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    what about 1/8 twist?
     
  9. Onmilo

    Onmilo
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    1-8 will shoot anything in the 52 to 77 grain catagory.

    The old favorite Match twist for shooting 80 grain bullets was 1-7.5

    I have found the 1-9 will stabalize the widest variety of bullet weights but does its best with 55-64 grain bullets.
     
  10. Kentak

    Kentak
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    It goes really, really fast out of the barrel, travels downrange, and, if you've done your part, hits what you're shooting at.
     
  11. marvin

    marvin
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    sci-fi nut

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    not out of a ar but my savage bolt had a 1-9 twist and would shot 77 grain bullets very well. some will some won't
     
  12. den308

    den308
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    With FMJ ammo, nothing other than hitting your target. With lighter jacketed bullets they may spin apart from the centrifugal force imparted by the rifling. An observant friend would see a puff of gray "smoke" about 15 yards out from the barrel.
     
  13. Petrie

    Petrie
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    So, the two questions I really wanted answered were will the heavier bullets fit in an AR magazine? And will the bullets fit in the chamber? I've heard that some real heavy .223 rounds are so long that the chamber throat has to be reamed and that the rounds have to be loaded one at a time through the side because they are too long to fit in the magazine. Is that only the 90 grain bullets they use in NRA long distance shooting or does that apply to 80 grain bullets? I'm curious because I bought some federal tactical 55 gr 5.56 that just fit in my AR mags, and I heard the heavier bullets are longer. Are the longer bullets just sunk further into the case? Is the overal cartridge length of a 77 gr Siera match king the same as a 55 grain cartridge?