rifle twist

outdoorsmen · 11-26-2003, 06:29 AM

I am thinking getting a Savage 12BVSS in 22-250. they say that the twist is 1-12, what bullet weight would that twist rate be good for?

mainehunt · 11-26-2003, 06:40 AM

The lighter bullets (30-55 grains) This is theoretically, the actual accuracy of your particular firearm may be different.

A rule of thumb is that the faster the rate of twist, the heavier the bullet.

outdoorsmen · 11-26-2003, 07:25 AM

this is what I don' t understand, if heiver bullet=fast twist rate what about the shotgun slug barrels and muzzleloaders that have 1-28" twist with big heavy bullets. 1-28" is slower than a 1-12" isn' t it?

mainehunt · 11-26-2003, 09:29 AM

Yeah, 1-28 is more than twice as slow as 1-12.

The shotgun slugs and muzzle loaders don' t need the faster twist because their velocity isn' t as fast. Also, they are much larger in diameter.

mainehunt · 11-26-2003, 09:33 AM

The heavier a bullet, in a given caliber, generally has to be longer in order to be heavier. (in most cases) That LONG, heavy bullet needs to have a faster RPM in order to stabilize it.

The shotgun slugs and muzzle loader slugs are NORMALLY slower, and shorter.

GordonGekko · 11-26-2003, 09:47 AM

The speed of the bullet and caliber will also influence the rate of twist. It will obviously take more spin to stabilize a long for caliber bullet like the 80 grain .22 cal bullets, than a shorter faster bullet like the 55 grain bullet in the same caliber. Traditionally, Gunsmiths have used the Greenhill Formula to determine the optimal twist for a particular bullet. The formula is T=150(d/r) for velocities from about 1500 to 2800 fps (substitute 180 for the 150 value for velocities exceeding 2800 fps). In the formula " T" is the twist rate. " d" is the bullet diameter. " r" is the bullet length to diameter ratio (length of bullet divided by diameter). So the total picture looks like this the three factors that influence twist are caliber, bullet length, and velocity.

Gordon

Vapodog · 11-26-2003, 10:36 AM

To the original question...years ago the .22-250, .220 Swift and .225 Winchester had 1-14 twist and worked well with bullets to 55 grains. Your 1-12 will easily handle 60 grain bullets.

outdoorsmen · 11-28-2003, 07:13 AM

what do you guys think about that gun in that caliber? I was debting the the 22-250 or the same gun in a .243 to shoot the 55gr. blistic tips. I have a .243 NEF ultra varmiter but I never shoot it to find out how accurite it is. the savage in .243 has a twist rate of 1-9.25"