What Twist for 30BR
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Al Nyhus writes in our 30BR guide:
"Barrel lengths from 21-24" work well, with the 24-inchers giving a very slight velocity edge, maybe 25-30 fps. As for twist rates, 1:17 and 1:18 barrels are winning the most matches. The 18-twist may have a slight accuracy edge, but Al Nyhus suggests sticking with a 1:17: "with the 1.00" jacketed bullets, a 1:17 is dandy and gives a bit of a safety net. A 1:18 is also great, but be aware that at least one well known barrel-maker's 18-twist 30BR barrels are actually about 1 in 18.25". When you run this close to the edge, bullet stability can get marginal in certain conditions". The 17- or 18-twist barrels also torque less than 1:15 barrels. This translates to easier gun-handling. Dick Grosbier explains: "the 17- and 18-twist barrels do not torque in the bags. They also do not copper-foul very much at all. Personally I believe 17- or 18-twist is the way to go. Craig Kostyshyn has only shot a 17 as far as I know and has a very enviable record with it. Both my Barrels are Kriegers as suggested by Joe and Henry."
If you want to shoot the 110-125gr FB match bullets, I would go 1:17. If you want to shoot heavier/longer hunting bullets, I'd go 1:11 for versatility.
"Barrel lengths from 21-24" work well, with the 24-inchers giving a very slight velocity edge, maybe 25-30 fps. As for twist rates, 1:17 and 1:18 barrels are winning the most matches. The 18-twist may have a slight accuracy edge, but Al Nyhus suggests sticking with a 1:17: "with the 1.00" jacketed bullets, a 1:17 is dandy and gives a bit of a safety net. A 1:18 is also great, but be aware that at least one well known barrel-maker's 18-twist 30BR barrels are actually about 1 in 18.25". When you run this close to the edge, bullet stability can get marginal in certain conditions". The 17- or 18-twist barrels also torque less than 1:15 barrels. This translates to easier gun-handling. Dick Grosbier explains: "the 17- and 18-twist barrels do not torque in the bags. They also do not copper-foul very much at all. Personally I believe 17- or 18-twist is the way to go. Craig Kostyshyn has only shot a 17 as far as I know and has a very enviable record with it. Both my Barrels are Kriegers as suggested by Joe and Henry."
If you want to shoot the 110-125gr FB match bullets, I would go 1:17. If you want to shoot heavier/longer hunting bullets, I'd go 1:11 for versatility.
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Dan Lilja, www.riflebarrels.com, has created a program that works via an Excel spreadsheet to calculate various bullet design parameters. If you input the bullet weight, length etc., it will generate a recommended twist rate.
Dan's Excel file is attached. You'll see numbers in the columns B and C. Replace those with the data from the bullet you want to use. The recommended twist rate will appear a few inches below, in Red Numbers. You'll need Excel,or compatible spreadsheet program) to run the numbers.
Dan's Excel file is attached. You'll see numbers in the columns B and C. Replace those with the data from the bullet you want to use. The recommended twist rate will appear a few inches below, in Red Numbers. You'll need Excel,or compatible spreadsheet program) to run the numbers.
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