Re: .32 Paul Jones Bullet
Posted: Sun Jan 06, 2019 7:21 am
And the Gyroscopic Stability Factor (Sg) for the two bullets:
Caliber 0.321 Inches
Bullet Weight 235.1 Grains
Bullet Length 1.299 Inches
Barrel Twist 11.5 Inches/turn
muzzle velocity 1400 fps
Temperature 50 degrees Fahrenheit (59 is standard)
Pressure 29.92 inches of mercury (29.92 is standard)
Sg = 1.84
Caliber 0.321 Inches
Bullet Weight 205 Grains
Bullet Length 1.134 Inches
Barrel Twist 14 Inches/turn
muzzle velocity 1400 fps
Temperature 50 degrees Fahrenheit (59 is standard)
Pressure 29.92 inches of mercury (29.92 is standard)
Sg = 1.60
Sg shouldn't be less than 1.4 (not enough spin - bullet is too long). If Sg is greater than about 2.0 (bullet starts to over spin), you may
gain some accuracy by going to a slower twist barrel or using a longer bullet.
I prefer an Sg between 1.8 and 2.0 and then I have no problems with changes in temperature or atmospheric pressure changing my Sg number.
If you have an Sg close to 1.4 you could result in atmospheric changes where your bullet will start to tumble (low temperatures or high pressure systems).
Caliber 0.321 Inches
Bullet Weight 235.1 Grains
Bullet Length 1.299 Inches
Barrel Twist 11.5 Inches/turn
muzzle velocity 1400 fps
Temperature 50 degrees Fahrenheit (59 is standard)
Pressure 29.92 inches of mercury (29.92 is standard)
Sg = 1.84
Caliber 0.321 Inches
Bullet Weight 205 Grains
Bullet Length 1.134 Inches
Barrel Twist 14 Inches/turn
muzzle velocity 1400 fps
Temperature 50 degrees Fahrenheit (59 is standard)
Pressure 29.92 inches of mercury (29.92 is standard)
Sg = 1.60
Sg shouldn't be less than 1.4 (not enough spin - bullet is too long). If Sg is greater than about 2.0 (bullet starts to over spin), you may
gain some accuracy by going to a slower twist barrel or using a longer bullet.
I prefer an Sg between 1.8 and 2.0 and then I have no problems with changes in temperature or atmospheric pressure changing my Sg number.
If you have an Sg close to 1.4 you could result in atmospheric changes where your bullet will start to tumble (low temperatures or high pressure systems).