fast to slow rifle twist

kentucky hareraiser · Posted: Thu Feb 18, 2010 4:01 pm Post subject: fast to slow rifle twist

i am cornfused Very Happy

would the 1:10 twist be considered slow or fast ? also 1:12 twist is it slower or faster than the 1:10 ,and the 1:28 twist in the muzzleloader would it be fast or slow..never could get all this straight.. i have 50 gr.v-max bullets and 55 gr. sp"s ,.,would both be good and accurat for both the 1:10 and 1:12 out of a 22-250

Aloysius · Posted: Thu Feb 18, 2010 4:06 pm Post subject: Re: fast to slow rifle twist

It's easy: 1 turn in 10" is much faster than 1 turn in 28". The first one almost turns 3 times before the second one makes 1 turn.

For your muzzleloader: the fast twist is for conicals, the slow for patched balls.

Grumulkin · Posted: Thu Feb 18, 2010 4:29 pm Post subject: Re: fast to slow rifle twist

In the 22-250, both a 1:10 and a 1:12 twist barrel will stabilize 50 and 55 gr. bullets well. They'll both probably do OK with even 60 gr. bullets. If you want to shoot 70 gr. bullets go with Speer 70 gr. Semi-Spitzers. For 80 gr. bullets, you would probably need a faster twist like 1:7 or 1:8.

The twist needed, by the way, is dependent on the bullet length which, of course, is somewhat related to bullet weight. A bullet with a long sharp point is harder to stabilize than the same weight of bullet in say a round nosed version.

Aloysius · Posted: Fri Feb 19, 2010 6:04 am Post subject: Re: fast to slow rifle twist

I think I now begin to understand the question and you indeed have to take into account the caliber.
So your muzzleloader with 1 in 28" is having a fast twist, so good for conicals. For patched balls twist is normally at least 2 times slower. It will be 1 in 66" or slower.

And when you compare the same caliber in a handgun and a rifle, the short barrel and lower speed of the handgun needs a slower twist to get the bullet stabilized.

Maybe you can compare it a little bit with burnrates of powder: a fast powder for a rifle will be slow or even very slow for a handgun or a shotgun.

Grumulkin · Posted: Fri Feb 19, 2010 6:42 am Post subject: Re: fast to slow rifle twist

Aloysius wrote:

And when you compare the same caliber in a handgun and a rifle, the short barrel and lower speed of the handgun needs a slower twist to get the bullet stabilized.

Maybe you can compare it a little bit with burnrates of powder: a fast powder for a rifle will be slow or even very slow for a handgun or a shotgun.

Twist in a handgun barrel should be at least as fast as what it should be for a rifle barrel. If anything, it should be faster because the velocity will be less and thus the spin rate of the bullet in rpm will be less.

In regards to fast vs slow powders, it isn't really true that "fast" powders are best without some qualification. If you're referring to small capacity straight walled handgun cartridge cases, it's pretty much true. For those who shoot bottlenecked rifle cartridges in handguns, it's not true. The same loads that give good accuracy in rifles are generally the ones to use in handguns.

Essentially all of the powder, providing the pressure is adequate, burns up completely in a very short length of barrel whether the powder is "slow" or "fast." I know this to be true for "rifle powder" even down to the 5 inch length of handgun barrel.

Aloysius · Posted: Fri Feb 19, 2010 7:05 am Post subject: Re: fast to slow rifle twist

You're right about the faster twist in a handgun. My mistake. It's only when they take rifle calibers in a handgun that they take a slower twist, maybe to stabilize the lighter bullets.

Grumulkin · Posted: Fri Feb 19, 2010 2:10 pm Post subject: Re: fast to slow rifle twist

The twist needed is related to bullet length. Of course, a heavier bullet of the same general profile will be longer but, if you take a round nosed bullet and a spitzer bullet of the same weight, the spitzer bullet will be longer and will need a faster twist to stabilize.

If the twist is marginal for a given bullet, velocity can make up for a marginal twist in part. Nevertheless, the bullet length remains the most important consideration regarding the twist needed irrespective of whether it's a handgun or a rifle.