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Thread: Barrel twist

  1. #1
    Boolit Master



    Join Date
    Feb 2018
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    Barrel twist

    Is there any kind of formula for calculating the best twist rate? Caliber, boolit weight, load, ft/sec, barrel length? Or is it just what has been known to preform well?
    Thanks

  2. #2
    Boolit Grand Master



    M-Tecs's Avatar
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    2nd Amendment of the U.S. Constitution. - "A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed."

  3. #3
    Boolit Bub bigbore52's Avatar
    Join Date
    Feb 2015
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    Australia
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    Greg,

    try Greenhill's ready made formula here :
    https://www.vcalc.com/wiki/AndrewBud...ing+Twist+Rate

    I've not used that link but the following Wiki link has the formula if you want to do it yourself:
    https://en.wikipedia.org/wiki/Alfred_George_Greenhill

    ....interesting most formulae such as Greenhill's rely on a constant and are limited to velocities sub 2400fps - I prefer to use Millers formula (based on Greenhills') that accounts for a greater number of variables including copper jacketed etc...
    His formula called the Miller Twist Rule can be found here

    https://en.wikipedia.org/wiki/Miller_twist_rule

    Hope they help.....

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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check