Twist rate vs killing power.

[JackinSD]

Can you explain how you derived those figures for me?

[Geo_Erudite]

Can you explain how you derived those figures for me?

Sure:

Bullet Mass:

M = w/g = (300 gr)/[7000 gr/lb * 32.2 ft/sec^2] = 0.00133 lb sec2/ft

32.2 ft/sec^2 = gravity

Kinetic Energy:

.5 * mass * angular velocity ^ 2

Angular Velocity:

2 * pi * bullet radius * revolution per second

[JackinSD]

Sure:

Bullet Mass:

M = w/g = (300 gr)/[7000 gr/lb * 32.2 ft/sec^2] = 0.00133 lb sec2/ft

32.2 ft/sec^2 = gravity

Kinetic Energy:

.5 * mass * angular velocity ^ 2

Angular Velocity:

2 * pi * bullet radius * revolution per second

Now that you have made the edit of your original post, I don't need to know how you came up with the numbers. They were originally not done correctly is why I was asking. They were 25-35 times what they should have been. Thanks for correcting them.

[Geo_Erudite]

Now that you have made the edit of your original post, I don't need to know how you came up with the numbers. They were originally not done correctly is why I was asking. They were 25-35 times what they should have been. Thanks for correcting them.

Yeah, I forgot to include our dear friend gravity in the kinetic energy equation, sorry about that.

[JackinSD]

Yeah, I forgot to include our dear friend gravity in the kinetic energy equation, sorry about that.

I saw the numbers and knew they had to be way out of whack. Did the calculations myself and was wondering if I had done something wrong. It had been a long time since I had used some of that math.
ha.