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What practice ammo for 1:7 twist?

Discussion in 'Handloading and Reloading' started by Doogledog, Sep 26, 2012.

  1. Doogledog

    Doogledog Well-Known Member

    I just purchase a BCM upper assembly with a 1:7 twist and I already have a DPMS rifle with a 1:9 twist. I have boatloads of 55gr ammo and I also reload. What is the most common bullet weight you all use for range time in your 1:7 twist rifles?
  2. MtnCreek

    MtnCreek Well-Known Member

    Hornady 55gr FMJ over 24.8gr IMR8208 in LC brass with either Win or CCI SR primers. Shoots good enough to keep ~75% on a 8" plate at 500yds. Most of the 25% of misses are me (if not all). At 300, at cow would have to step on me to miss. :)
  3. Reloadron

    Reloadron Well-Known Member

    1:7 Twist I like 69 to 80 grain bullets. You don't mention store bought or roll your own?

  4. Doogledog

    Doogledog Well-Known Member

    Could be either. I just noticed most bulk ammo (store bought) is 55 to 62 grains. I'm well aware the tighter the twist the heavier bullet weight can be stabilized but, I just wondered what most other guys used. I'm very new to the 1:7 twist rate.
  5. minutemen1776

    minutemen1776 Well-Known Member

    I mostly shoot XM193 (55-grain) in my BCM 1:7 upper. I can tell no difference between it and the heavier stuff.
  6. brickeyee

    brickeyee Well-Known Member

    Unless the rifle is VERY accurate you will not be able to tell if you spin a lighter bullet faster than minimum (or the bullets have real weight distribution non-uniformity).
  7. Doogledog

    Doogledog Well-Known Member

    Based on the responses to my question, shooting lighter weight bullets through a tighter twist is more forgiving than the opposite. Is that an accurate assumption?
  8. Reloadron

    Reloadron Well-Known Member

    Pretty much seems to work out that way. :)

    Since frequently we have the barrel we have it becomes a matter of working up loads (the beauty of roll your own) that work best in the rifle.

  9. cfullgraf

    cfullgraf Well-Known Member

    With a short barrel, 223 Remington rifle you probably cannot spin a bullet fast enough for it to disintegrate.

    The higher the velocity, the faster the spin of the bullet for a given twist rate, in other words more RPM (revolutions per minute).

    With the large case 22 caliber rifles such as 22-250, 220 Swift, etc, they can get light bullets spinning too fast and the bullet disintegrates upon leaving the barrel. That is one reason the twist on those rifles tend to be slower than ARs.
  10. moxie

    moxie Well-Known Member

    I use 55 gr. factory loads and 55gr. for reloading. You can buy them in bulk, ammo or bullets, for a lot less than most others. By the way, bulk Lake City M193 was about .30 cents per round around a year ago, and is now about .40 on sale.

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