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July 3, 2014
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Is there a difference in twist rate between small frame revolvers and the large frame? What? Is there a twist difference between small frame common B/As (2.5-4-6-8) and the silhouete B/As (10-12-15)? I read somewhere there was , but they did not say exactly what, all they said was they where slower for heavier bullets. TIA
February 16, 2016
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Found information and a twist rate table, by manufacturer, at Exterior Ballistics
32 H&R Magnum - 1 in 18-3/4"
38 Special - 1 in 18-3/4"
357 Magnum -1 in 18-3/4"
357 Magnum - 1 in 14" (10”,12”, 15” barrels only)
357 Maximum - 1 in 18-3/4"
375 Super Mag - 1 in 18-3/4"
41 Magnum -1 in 18-3/4"
44 Magnum - 1 in 18-3/4"
44 Magnum - 1 in 20"
445 Super Mag - 1 in 18-3/4"
July 3, 2014
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Stinger, thank you. For clarification is twist rate faster or slower for heavier bullets, kinda foggy this morning. What I was thinking of doing was altering my 15" B/A to go on my 40.
February 16, 2016
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decoyme said
For clarification is twist rate faster or slower for heavier bullets ?
The heavier the projectile, the slower the twist rate, so the higher the ratio number (1:5 is faster than 1:10). The constant of 1 equals one full rotation of the bullet and the second number is how many inches it takes to accomplish it.
July 3, 2014
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May 26, 2015
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Thank you, I've always wondered about that.
July 3, 2014
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We are here to edify, educate and elucidate when we can. Sometimes we're just lucky.
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March 17, 2016
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Is there a difference in twist rate with regard to load, i.e. 22-22 mag I see there is in the 357- 357 max, 44 mag - 445 SM. Any idea why twist rate increase in those?
February 16, 2016
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CaptDanDD said
Is there a difference in twist rate with regard to load, i.e. 22-22 mag?
Twist rate uses both bullet weight and velocity variables, to derive the appropriate ratio. It has to do with moving mass to a certain velocity within a specific time duration. A heavier mass requires a slower twist than a lighter mass to start rotating. If you increase velocity, the mass is moving quicker down the barrel, so with the same twist, it would be trying to rotate the mass too fast, so they slow the twist rate the faster the velocity is.
If you push a bicycle down the street, you can easily start running immediately. If you push a motorcycle, you have to start off slower, to get the mass moving.
February 16, 2016
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I noticed that all EWK .357 Magnum barrels are 1:12 for 2-1/2" thru 10" lengths.
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March 17, 2016
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Stinger said
CaptDanDD said
Is there a difference in twist rate with regard to load, i.e. 22-22 mag?Twist rate uses both bullet weight and velocity variables, to derive the appropriate ratio. It has to do with moving mass to a certain velocity within a specific time duration. A heavier mass requires a slower twist than a lighter mass to start rotating. If you increase velocity, the mass is moving quicker down the barrel, so with the same twist, it would be trying to rotate the mass too fast, so they slow the twist rate the faster the velocity is.
If you push a bicycle down the street, you can easily start running immediately. If you push a motorcycle, you have to start off slower, to get the mass moving.
It looks like they are increasing the twist rate on the higher velocity, or am I reading the chart numbers incorrectly?
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March 17, 2016
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CaptDanDD said
Stinger said
CaptDanDD said
Is there a difference in twist rate with regard to load, i.e. 22-22 mag?Twist rate uses both bullet weight and velocity variables, to derive the appropriate ratio. It has to do with moving mass to a certain velocity within a specific time duration. A heavier mass requires a slower twist than a lighter mass to start rotating. If you increase velocity, the mass is moving quicker down the barrel, so with the same twist, it would be trying to rotate the mass too fast, so they slow the twist rate the faster the velocity is.
If you push a bicycle down the street, you can easily start running immediately. If you push a motorcycle, you have to start off slower, to get the mass moving.
It looks like they are increasing the twist rate on the higher velocity, or am I reading the chart numbers incorrectly?
Never mind, damn dyslexia.... I see my error in calculation. My bad!
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February 22, 2009
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More than you ever want to know about external ballistics can be found on the JBM website. Ron
Technically, the glass is always full; half liquid, half air....
February 16, 2016
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rwsem said
More than you ever want to know about external ballistics can be found on the JBM website.
Thanks for sharing Ron .. I'm currently enthralled with Don Miller's article; "A New Rule for Estimating Rifling Twist An Aid to Choosing Bullets and Rifles".
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