Appropriate twist rate for tokarev barrel?

knapwon · July 2, 2016, 01:58 PM

Hello, I'm planning to make two new barrels (one 7.62 and one 9mm) for my Yugo M57 (tokarev) pistol and I'm a bit confused on selecting a rate of rifling twist for best accuracy.
Normally I use Miller's twist rate formula to determine what's the best twist rate for a particular bullet, but this time around there's a huge discrepancy between what Miller's formula suggests vs the original barrel it makes me wonder if I'm missing some critical information about twist rates.

For example, with Miller's formula, it suggests 1:24 works for both 7.62x25 and 9x19, but factory barrels in both calibers seem to favor 1;10 instead. From my handloading experience with rifle loads too much twist or spin on the bullet is detrimental to accuracy, and way excessive twist can cause the bullet to keyhole like as if it doesn't have enough spin.

Can someone clear this up for me? Why pistol barrels use such a fast rate of twist far more than needed for pistol bullets? Help is very appreciated.

**JohnKSa** · July 2, 2016, 02:22 PM

Assuming that you stabilize the bullet adequately and don't spin it so fast that it self-destructs when it exits the muzzle, it's a non-issue.

In recoil-operated, semi-auto handguns there are so many other factors that affect accuracy dramatically more than twist that it's not worth worrying about twist.

Go with 1:10 if that's what manufacturers typically use. It will work fine. If the barrel isn't accurate it will NOT be due to the twist unless you go so slow that the bullet doesn't stabilize.

knapwon · July 2, 2016, 08:05 PM

Thanks JohnKSa!

Jim Watson · July 2, 2016, 10:21 PM

I don't know where Ol' Georg and DWM got a 250mm (10") twist for 9mm.
American 9mms are usually but not always 16" twist.
Weigand agrees with your calculation at 24".

I suspect the 10 twist of the 7.62.Tok is shared with Mosin Nagant and PPSh for convenience in barrel tooling.
The M1 Carbine gets by with a 20" twist.

As JohnK says, there are other factors, the most important being fit in the gun.

Gunplummer · July 3, 2016, 12:03 AM

The PPSH is 1-10. It is a hot little round.

Clark · July 12, 2016, 08:56 AM

I did 1 twist in 10" with this 7.62x25mm long barrelled Tokarev in this 2006 project. With S&B 85 gr ammo I shot one 5 shot group. It was 2.33" at 100 yards. I know I could do better.

Dixie Gunsmithing · July 12, 2016, 12:17 PM

Clark, that looks like one that I saw in Star Wars!

Clark · July 12, 2016, 10:24 PM

Since 2006 I have helped on an R2D2 Robot in my shop.
Many of the same machines that made the Tokarev made the robot.

The Tokarev barrel and scope mount was ~~$150 invested my money.
R2D2 was ~~$30k invested in parts, some else's money and my free labor.

michaeldarnold · July 13, 2016, 11:44 AM

^^^NICE!^^^ The gun too.

July 2, 2016, 01:58 PM	#1
knapwon Junior Member Join Date: June 30, 2016 Location: SoCal Posts: 7	Appropriate twist rate for tokarev barrel? Hello, I'm planning to make two new barrels (one 7.62 and one 9mm) for my Yugo M57 (tokarev) pistol and I'm a bit confused on selecting a rate of rifling twist for best accuracy. Normally I use Miller's twist rate formula to determine what's the best twist rate for a particular bullet, but this time around there's a huge discrepancy between what Miller's formula suggests vs the original barrel it makes me wonder if I'm missing some critical information about twist rates. For example, with Miller's formula, it suggests 1:24 works for both 7.62x25 and 9x19, but factory barrels in both calibers seem to favor 1;10 instead. From my handloading experience with rifle loads too much twist or spin on the bullet is detrimental to accuracy, and way excessive twist can cause the bullet to keyhole like as if it doesn't have enough spin. Can someone clear this up for me? Why pistol barrels use such a fast rate of twist far more than needed for pistol bullets? Help is very appreciated.

July 2, 2016, 02:22 PM	#2
JohnKSa Staff Join Date: February 12, 2001 Location: DFW Area Posts: 24,972	Assuming that you stabilize the bullet adequately and don't spin it so fast that it self-destructs when it exits the muzzle, it's a non-issue. In recoil-operated, semi-auto handguns there are so many other factors that affect accuracy dramatically more than twist that it's not worth worrying about twist. Go with 1:10 if that's what manufacturers typically use. It will work fine. If the barrel isn't accurate it will NOT be due to the twist unless you go so slow that the bullet doesn't stabilize. __________________ Do you know about the TEXAS State Rifle Association?

July 2, 2016, 08:05 PM	#3
knapwon Junior Member Join Date: June 30, 2016 Location: SoCal Posts: 7	Thanks JohnKSa!

July 2, 2016, 10:21 PM	#4
Jim Watson Senior Member Join Date: October 25, 2001 Location: Alabama Posts: 18,537	I don't know where Ol' Georg and DWM got a 250mm (10") twist for 9mm. American 9mms are usually but not always 16" twist. Weigand agrees with your calculation at 24". I suspect the 10 twist of the 7.62.Tok is shared with Mosin Nagant and PPSh for convenience in barrel tooling. The M1 Carbine gets by with a 20" twist. As JohnK says, there are other factors, the most important being fit in the gun.

July 3, 2016, 12:03 AM	#5
Gunplummer Senior Member Join Date: March 11, 2010 Location: South East Pa. Posts: 3,364	The PPSH is 1-10. It is a hot little round.

July 12, 2016, 12:17 PM	#7
Dixie Gunsmithing Moderator Emeritus Join Date: April 27, 2013 Location: Ohio Posts: 1,923	Clark, that looks like one that I saw in Star Wars!

July 13, 2016, 11:44 AM	#9
michaeldarnold Senior Member Join Date: April 8, 2016 Location: St. Louis Suburbs Posts: 137	^^^NICE!^^^ The gun too.