You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an alternative browser.
You should upgrade or use an alternative browser.
Powder and spin rate
- Thread starter Dano4734
- Start date
Dano4734 wrote:
Does a slower burning powder take better advantage of the rifling and hence spin.
In general, No.
Whether a fast burning powder pushes the bullet out of the muzzle in 125 microseconds as opposed to a slow burning powder doing it in 165 microseconds (these are notional times, depending on the powder and length of the barrel we could be talking 52 and 67 microseconds, respectively), there is no way to characterize what is going on as anything other than the bullet being "shoved" down the barrel.
The simple answer to the posed question is "No."
The rpm of a rifle bullet as it exits the muzzle is determined by its muzzle velocity and the rifling twist rate.
For example:
Assume: Twist rate = 1:10; muzzle velocity = 2,000 fps.
2,000 fps equals 120,000 fpm (feet per minute).
120,000 fpm equals 1,440,000 ipm (inches per minute).
At a twist rate of 1:10, bullet makes one revolution per 10 inches of travel; in 1,440,000 inches of travel, it would make 144,000 revolutions, or 144,000 rpm.
This does not imply that rpm will remain constant over time of flight, but does calculate rpm at the moment of muzzle exit, which, as noted, is fixed entirely by twist rate and MV.
The only effect that propellant burn rate (or propellant charge, or any other factor) can have on muzzle exit rpm is any effect it might have on muzzle velocity.
The rpm of a rifle bullet as it exits the muzzle is determined by its muzzle velocity and the rifling twist rate.
For example:
Assume: Twist rate = 1:10; muzzle velocity = 2,000 fps.
2,000 fps equals 120,000 fpm (feet per minute).
120,000 fpm equals 1,440,000 ipm (inches per minute).
At a twist rate of 1:10, bullet makes one revolution per 10 inches of travel; in 1,440,000 inches of travel, it would make 144,000 revolutions, or 144,000 rpm.
This does not imply that rpm will remain constant over time of flight, but does calculate rpm at the moment of muzzle exit, which, as noted, is fixed entirely by twist rate and MV.
The only effect that propellant burn rate (or propellant charge, or any other factor) can have on muzzle exit rpm is any effect it might have on muzzle velocity.