Useful Info
 

I thought some people might find this interesting
Useful info


Some useful values:
1 grain = 0.037 dram
1 pound = 7000 grains
1 pound = 16 ounces
1 ounce = 437.5 grains
1 ounce = 16 drams
1 dram = 27.344 grains
Density of lead is 11.34 gram/cc
1 gram =15.4324 grains
1 inch = 2.54 centimeters
1 meter = 39.37 inches, 3.28 feet and 1.09 yards
pi = 3.14159
Volume of a sphere = 4/3pi R3 (4/3 x pi x radius of sphere cubed)
Radius of a sphere = cube root of (3Volume/4 pi)
Volume x density = weight

To find Twist needed for a bullet

150 x diameter squared divided by bullet length = required spin
Example for a .45 caliber bullet .60 inches long:
150 x .45 x .45 divided by .60 = 50.6 inches
So, for the example bullet, a spin rate of 1:50.6 or faster is required

RE: Useful Info
 

Thanks for that Lee. I've been looking for that twist rate formula.

I have a hankering to build a trim little gun that would shoot the Hornady 90 grain .315 (32 caliber) Lead Semi Wad Cutters. Now all I have to do is find a shallow groove .314 barrel in 1:24 twist. :D

RE: Useful Info
 

Lee

Thank you... i copied and placed it in the ML archives...

thanks