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.
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.
