barrel twist vs bullet lenght and barrel lenght

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  • BIG D
    Unwashed
    • Jan 2017
    • 14

    barrel twist vs bullet lenght and barrel lenght

    what is the best bullet to twist and barrel lenght ? i have a 19.5'' shilen 1 in 9 twist barrel.
  • rabiddawg
    Chieftain
    • Feb 2013
    • 1664

    #2
    Speaking in generalities here, heavier pills prefer faster twist rates lighter pills prefer/require slower twist rates.

    I have read a post by Bill A. saying that longer length barrels >18 do fine with 8-9 twists. Shorter barrels will benefit from a faster twist like 7.5. I'm paraphrasing here so if you want, search Bill A's posts.

    I searched the old posts, couldn't find it. It may have been lost in the crash.
    Last edited by rabiddawg; 07-24-2017, 02:56 AM.
    Knowing everthing isnt as important as knowing where to find it.

    Mark Twain

    http://www.65grendel.com/forum/showt...2-Yd-Whitetail

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    • Kilco
      Chieftain
      • Jan 2016
      • 1201

      #3
      Your 1:9 will do fine with the 123gr pills. Never tried 130s in my 20" 1:9.

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      • VASCAR2
        Chieftain
        • Mar 2011
        • 6218

        #4
        Here is a link to a barrel twist calculator.





        Each barrel is unique, some may shoot longer bullets better with 1:9 twist than another barrel with 1:9 twist. This might be because the actual twist might vary a little from manufacturing tolerances, one barrel might be a little faster than 1:9 and another might be a little slower than 1:9. I've seen this happen when shooting 1:9 twist barrel with 5.56/223 barrels and 70 + grain bullets. I think the longer 20"-24"barrels do a better job stabalizing a bullet than a 16" or shorter barrel.

        My Son in Law has a 22" 1:9 twist Lothar Walther 6.5 Grendel and it shoots Hornady 129 grain SST really well. The longer bullets generally need the faster twist. The monolithic bullets are generally long for their weight compared to cup and core bullets.

        There is a wide variety of 264/6.5 bullets on the market and the trend to shoot at longer range has moved manufactures to offer 1:8 or faster twist for the 6.5 Grendel. In years past manufactures commonly used 1:9 twist for the 264 Winchester Magnum, 6.5 Carcano and other 6.5/264 caliber cartridges.

        If I were buying a new 6.5 Grendel I'd prefer a 1:8 twist. My 20 Shilen 6.5 Grendel is 1:9 twist but I haven't tested it with bullets heavier than 125 grains. My 16" 6.5 Grendel with 1:9 twist has kept 123 grain match bullets stable to 800 yards.

        I've shot 100 grain Barnes TTSX which is a long bullet in my 16" 1:9 twist 6.5 Grendel with good results. One of these days I'd like to test my 16" & 20" 1:9 twist 6.5 Grendels with Nosler 129 grain ABLR, 130 grain Berger and 129 grain Hornady SST.
        Last edited by VASCAR2; 07-24-2017, 08:57 PM.

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