twist on ar barrels

gitthatdawg2

March 18, 2004 19:25

I am buying a ar-15 type rifle and did not know what was better 1-8 twist or 1-9 twist i have been told that the 1-8 works good with lighter grain bullets

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  OleDuk

  March 18, 2004 19:35

  I'm sure other guys can give you more detailed info, but generally,the faster twist rate is better with the heavier bullets, caliber for caliber. Those match shooters who shoot AR's in long range competition with heavy bullets use rates as fast as 1:7, or 1:7-1/2. The slower rates are better for the lighter bullets; .22 caliber center-fire rifles for 50 or 55 grain bullets use 1:14 twist.
  Cheers,
  OleDuk[:)]

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  v35

  March 19, 2004 07:20

  I would be favoring the 1 in 8 twist. Take a look at AR15.Com and see what they say.
  Olympic Arms made very good barrels. Try their website
  for their recommendations.
  I have one of their 1 in 9, 16" SS barrels that shoots 55 gr bullets very well.

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  Txs

  March 19, 2004 07:25

  AR type rifles are generally equipped with either 1:7, 1:9 or 1:12 barrels. The M16/M16A1 GI barrels were 1:12 and designed to shoot 55 gr. M193 bullets. The M16A2 barrels are 1:7 to stabilize the 62 gr. M855 bullet.
  
  Keep in mind that this 1:7 twist rate may not apply to all 62 gr. bullets. The M855 bullet is a composite design, with a small diameter steel core, and is longer than a comparable weight lead core bullet.
  
  Most AR's you see manufactured recently, including the Colt, are equipped with 1:9 barrels to split the difference and shoot either 55 or 62 gr. bullets.

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  Invicta

  March 19, 2004 08:14

  1:8 is for heavier bullets like a 68 or 69 grainer
  1:9 is for lighter bullets 55-65 grains

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