32-20 Rate of Twist

[seawolfjack]

Hello everyone, can anyone explain why the 32-20's twist is 1-22 or 1-20. It's higher than the 22's{218,22Hornet,25-20}. I know the bullet size is .3125 to .313. Now all the other .312 barrels are 1-9.75 or 1-12. I know that the Mosin and Argentine Mauser, the 303 Brit are all military weapons and they were designed to fire larger bullets. Could I get away with a barrel with a slower twist? Where do I find the info on Greenhills stuff?? Or is it C.E. Harris?? Having a hard time fiquring this out. Any help would be appreciated. Have Fun

[9.3X62AL]

Jack--

The 32-20 WCF in rifles started life as a blackpowder caliber using 115-120 grain boolits/bullets at ~1200 FPS, and the 1-20" to 1-22" twist rate is a good pitch for those conditions. The twist rate didn't get upgraded when the caliber got updated to the 30 U.S. Carbine, likely because the upgraded caliber used the same weight-class bullets as its precursor chambering. If heavier bullets are on the horizon, nominal 30 caliber (.308" groove) barrels with 1-10" to 1-12" twists get some use with this caliber, sometimes referred to as the "30-20". Others here might have experience with this variant--my time with 32-20 is limited to the fatter boolits and conventional weights in revolvers and lever carbines. FWIW, Starline brass might be the best thing to happen to this caliber since its inception.

A Google search on "Greenhill Formula" should yield info on the subject.

[Boz330]

http://www.uslink.net/~tom1/twistrate.htm

Try the above site and plug in your numbers and it will give optimum twist, bullet length, or velocity.

Bob