18-04-2014, 08:56 PM
(This post was last modified: 18-04-2014, 09:50 PM by Drew Phipps.)
I went out and bought a 99 cent plastic protractor and measured the angle of the scratch created by lands/groove on the above photos of CE 399. I used the cannellure as a reference line, assuming that it is perpendicular to the long axis of the bullet. Just as I suspected, photos 3317 and 3319 show an angle of 84 degrees, and photos 3318 and 3320 show an angle of 86 degrees. Quite impossible for a single bullet.
from there, we can calculate the spin rate of each bullet IF WE ASSUME we know its diameter.
From Bob's research we have 2 possible bullet diameters (available in 1964): .268 inches (Italian mil spec) and .264 inches (WCC). I'm going to also throw in 6.5 mm ammo = .256 inches (because Frazier testifies that its the same, and also because it is the closest measurement to the average width measurement I got from averaging all 4 photos together in a previous post, when I pretended that all 4 pics were of the same bullet). I am also adding 8 mm (.315 inches) ammo (some of the 1938 carbines were converted to 8mm (Mauser) ammo) and 7.35 mm (.289 inches), the intended caliber of the 1938 short rifle. If I remember my high school trig correctly...
CE 3317 and 3319 (84 degrees) .268 spin = 1 / 8.01 inches
.264 spin = 1 / 7.89 inches
.256 spin = 1 / 7.66 inches
.315 spin = 1 / 9.42 inches
.289 spin = 1 / 8.65 inches
CC 3318 and 3320 (86 degrees) .268 spin = 1 / 12.01 inches
.264 spin = 1 / 11.84 inches
.256 spin = 1 / 11.49 inches
.315 spin = 1 / 14.13 inches
.289 spin = 1 / 12.95 inches
As you can see photos 3317 and 3319 are bullets that spin too fast (smaller ratio is a faster spin) to have been shot from the rechambered 91/38 short rifle, and must have fired from the carbine (if fired from a carcano at all), UNLESS the round is actually .289 (7.35 mm ammo) fired from a 1938 rifle. 3318 and 3320 spin too slowly to have been fired from the 91/38 short rifle with the standard barrel (or the carbine), but it might be possible to get these spins from a 91/38 with a sawed off progressive barrel. So we have 2 different bullets fired from 2 different guns and all 4 pictures kludged together by the FBI to masquerade as the single bullet.
from there, we can calculate the spin rate of each bullet IF WE ASSUME we know its diameter.
From Bob's research we have 2 possible bullet diameters (available in 1964): .268 inches (Italian mil spec) and .264 inches (WCC). I'm going to also throw in 6.5 mm ammo = .256 inches (because Frazier testifies that its the same, and also because it is the closest measurement to the average width measurement I got from averaging all 4 photos together in a previous post, when I pretended that all 4 pics were of the same bullet). I am also adding 8 mm (.315 inches) ammo (some of the 1938 carbines were converted to 8mm (Mauser) ammo) and 7.35 mm (.289 inches), the intended caliber of the 1938 short rifle. If I remember my high school trig correctly...
CE 3317 and 3319 (84 degrees) .268 spin = 1 / 8.01 inches
.264 spin = 1 / 7.89 inches
.256 spin = 1 / 7.66 inches
.315 spin = 1 / 9.42 inches
.289 spin = 1 / 8.65 inches
CC 3318 and 3320 (86 degrees) .268 spin = 1 / 12.01 inches
.264 spin = 1 / 11.84 inches
.256 spin = 1 / 11.49 inches
.315 spin = 1 / 14.13 inches
.289 spin = 1 / 12.95 inches
As you can see photos 3317 and 3319 are bullets that spin too fast (smaller ratio is a faster spin) to have been shot from the rechambered 91/38 short rifle, and must have fired from the carbine (if fired from a carcano at all), UNLESS the round is actually .289 (7.35 mm ammo) fired from a 1938 rifle. 3318 and 3320 spin too slowly to have been fired from the 91/38 short rifle with the standard barrel (or the carbine), but it might be possible to get these spins from a 91/38 with a sawed off progressive barrel. So we have 2 different bullets fired from 2 different guns and all 4 pictures kludged together by the FBI to masquerade as the single bullet.