Do You Doubt The PRB?
12-24-2015, 06:10 PM
#321
Banned
Join Date: Oct 2015
Posts: 146
Pete,
And one of the worst things is, its not linear. It is linear up until you reach the speed of sound. Right above that threshold, wind drift and velocity increase for the next few hundred FPS. The explanation for this that I heard is that this effect is due to the sonic wave moving back on the projectile. Once it gets entirely behind the projectile, things get back to normal. And this is the problem with the roundball. Drive it 1800, and it will quickly lose velocity and drop into this zone of increased wind drift. Note that BC doesn't affect this zone, it just lessens the magnitude. and how quicky you lose velocity and enter this zone. The oldtimers knew this, which was why they kept their loads subsonic. It wasn't until the advent of relatively smallbore cartridges and smokeless powder that they were able to keep their speeds transonic all the way to the target, avoiding the speed of sound region.
This is why I view the roundball so poorly. It has the shape that is most affected by wind, and it commonly flies at speeds where the wind drift is worst. Its a double whammy. What's funny about this is the projectiles that are better still have limitations. All these pistol bullets in sabots are barely more powerful that a .44 magnum carbine. Not that that's bad, and its a lot better than the .44-40, the most popular round in eastern deer camps in 1900. The .30-30 was relatively new, 1895, and was a real rocket. It wasn't until the '40s, '50s, and maybe early '50s that the thuttythutty was on the decline. But what most sabot shooters are using isn't any Weatherby. Or even a .300 Mag.
OldBob
And one of the worst things is, its not linear. It is linear up until you reach the speed of sound. Right above that threshold, wind drift and velocity increase for the next few hundred FPS. The explanation for this that I heard is that this effect is due to the sonic wave moving back on the projectile. Once it gets entirely behind the projectile, things get back to normal. And this is the problem with the roundball. Drive it 1800, and it will quickly lose velocity and drop into this zone of increased wind drift. Note that BC doesn't affect this zone, it just lessens the magnitude. and how quicky you lose velocity and enter this zone. The oldtimers knew this, which was why they kept their loads subsonic. It wasn't until the advent of relatively smallbore cartridges and smokeless powder that they were able to keep their speeds transonic all the way to the target, avoiding the speed of sound region.
This is why I view the roundball so poorly. It has the shape that is most affected by wind, and it commonly flies at speeds where the wind drift is worst. Its a double whammy. What's funny about this is the projectiles that are better still have limitations. All these pistol bullets in sabots are barely more powerful that a .44 magnum carbine. Not that that's bad, and its a lot better than the .44-40, the most popular round in eastern deer camps in 1900. The .30-30 was relatively new, 1895, and was a real rocket. It wasn't until the '40s, '50s, and maybe early '50s that the thuttythutty was on the decline. But what most sabot shooters are using isn't any Weatherby. Or even a .300 Mag.
OldBob
