Left Hand Twist Barrel Manufacturers

Noobilicious

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Oct 27, 2021
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I played with some ballistic calc numbers, and noticed that left-hand vs right-hand twist difference becomes larger and larger as barrel twist rate becomes faster. For old slower twist barrels, the difference between L vs R is small enough to be negligible. But for 1:7 twist barrels shooting 6 Creedmoor, L twist was 16" closer to the target at 1000 yards compared to R twist!

So I am thinking of trying a left twist for my next long-range build. Who are the manufacturers that offer left twist barrels (besides Bartlein)?

Thanks!
 

KnowNothing256

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  • Jan 9, 2020
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    I played with some ballistic calc numbers, and noticed that left-hand vs right-hand twist difference becomes larger and larger as barrel twist rate becomes faster. For old slower twist barrels, the difference between L vs R is small enough to be negligible. But for 1:7 twist barrels shooting 6 Creedmoor, L twist was 16" closer to the target at 1000 yards compared to R twist!

    So I am thinking of trying a left twist for my next long-range build. Who are the manufacturers that offer left twist barrels (besides Bartlein)?

    Thanks!
    Is that true shooting both due north and due south, when you plug both into your solver?
     

    pmclaine

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  • Nov 6, 2011
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    I've got a Bartlein left hand Gain Twist being built in this saga....


    Think it's reaching the final stages of production.

    Think the big thing I will notice will be the rifle torquing into my body vs away.
     
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    Noobilicious

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    Oct 27, 2021
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    Thanks all!

    Bartlein's current lead time is 12 months, so I am looking around for a faster option if possible. I will reach out to K&P and Hart about L barrels.
     

    Noobilicious

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    Oct 27, 2021
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    Is that true shooting both due north and due south, when you plug both into your solver?
    Not sure - I cannot find the option to enter compass bearing on JBM ballistic calc.

    If your software allows you to check this, I will appreciate you sharing the results. (6 CM, 112 grain, BC = 0.6, 3000 fps, 7 twist)
     

    Flyingbullseye

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    Mark Chanlynn does some of his barrels left handed. Can't recommend his barrels enough if he is still making them.

    I'm all but positive that his 6 and 6.5mm barrels can or are done left handed.
     
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    KnowNothing256

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    Not sure - I cannot find the option to enter compass bearing on JBM ballistic calc.

    If your software allows you to check this, I will appreciate you sharing the results. (6 CM, 112 grain, BC = 0.6, 3000 fps, 7 twist)

    You're right, I couldn't find the target azimuth entry on JBM either, looks like that solver doesn't include Coriolis. However, using JBM and your data (although I went with the manufacturer's BC for the 112gr Matchburner of 0.624 G1), here's what I got:

    1637992865605.png


    So you're only closer to the target if the wind is in the favorable direction. Try switching the wind direction in your original test to 180 degrees opposite and see if the left twist gets you closer to the target then; I expect it'll be farther away, by the same difference you saw the first time.
     

    Noobilicious

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    Oct 27, 2021
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    You're right, I couldn't find the target azimuth entry on JBM either, looks like that solver doesn't include Coriolis. However, using JBM and your data (although I went with the manufacturer's BC for the 112gr Matchburner of 0.624 G1), here's what I got:

    View attachment 7748490

    So you're only closer to the target if the wind is in the favorable direction. Try switching the wind direction in your original test to 180 degrees opposite and see if the left twist gets you closer to the target then; I expect it'll be farther away, by the same difference you saw the first time.

    Ahhh I get it now! Thanks for walking me through this.
     
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