19-04-2014, 01:02 AM
Drew Phipps Wrote: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.
I think another strong contender for the photo of CE 399 could be a .25 calibre bullet (.257" diameter), as many of Frazier's measurements would seem to correspond with a bullet of that calibre.
Interesting thought, regarding the M91/38 being made from a cut down M91 long rifle barrel with progressive twist rifling. I don't know whether or not you have read the thread I posted concerning the history of the short rifle so I will give you a brief synopsis.
The M38 short rifle made its debut in 1938. The 6.5x52mm cartridge was to be scrapped forever and to be replaced with the 7.35x51mm cartridge. Everything about the 6.5mm rifle (bolt, receiver, magazine, etc.) stayed the same in the new rifle, including the cartridge. Only the neck was expanded to accept the larger diameter bullet.
A radical idea was introduced into the 7.35mm bullet. First, the bullet was pointed instead of round nosed, inducing the bullet to tumble upon hitting bone and cause greater damage. Second, inside the jacket, the front third of the bullet was made of aluminum, instead of lead, while the rear two-thirds of the bullet was made from lead. This imbalance in mass between front and back end of this bullet further enhanced the tumbling effect, and made these bullets even more deadly. To understand where they got the idea for this bullet, Google the .303 British Mk. VII cartridge.
The thing that must be understood is that it was possible to effect all of these bullet changes to the 6.5x52mm cartridge, and be just as successful. There was no ballistic reason to go to a larger diameter bullet.
The reason it was decided to go to the 7.35mm calibre is that the Italians planned to cut the 31 inch barrels of worn out M91 long rifles down to 21 inches and recycle them as M38 short rifle barrels. Each cut down barrel would be bored out to a new bore diameter of 7.35 mm and this would effectively remove all traces of the 6.5mm rifling grooves. It was actually a very sound idea and, considering Italy's limited steel resources, freed up a lot of steel that could go into other weapons.
Below are two photos of 6.5mm Carcanos made prior to 1938.
As you will notice, there are five flat facets machined onto the base of the barrel, just behind the rear sight.
Below is a photo of a 7.35mm Carcano short rifle:
Notice the flat facets are absent and the chamber is now round in shape, and somewhat smaller than the pre-1938 chambers. Here are another two photos, one of them quite famous:
As it is an established fact that ALL 7.35mm barrels were cut down 31 inch M91 barrels, the only possibility that exists is that the barrels were put in a lathe and the flat facets machined down, leaving only a round chamber and effectively removing all stampings that would ID this barrel as an M91 barrel. In the photo above C2766, you can see where the machinist did not take quite enough metal off, leaving the forward points of the facets intact.
As they were, in effect, making an entirely new barrel and rifle, and not a re-work, they had every right to begin afresh with the stampings. However, the round shape of the chamber, which was retained even after the 7.35mm was discarded and the 6.5mm was brought back, opened up other possibilities.
When the 7.35mm M38 short rifle was discarded in 1939 and the 6.5mm M91/38 short rifle was introduced in 1940, it must be understood that it was no longer possible to recycle 31 inch M91 long rifle barrels (progressive twist) in their manufacture, as the M91/38 had standard twist rifling, and attempting to re-machine standard twist rifling over top of the M91 progressive twist rifling was impossible. It must also be understood that Italy began the manufacture of M91/38's in 1940 with NO 6.5mm short rifle barrels stockpiled, and they also declared war on the Allies in 1940. This declaration of war led to the immediate impounding of a good portion of Italy's merchant fleet in harbours around the world. As Italy's steel production was only a fraction of other European nations, a good part of their steel industry was dependent on imports.
Where did they get enough steel to make all of the new M91/38 short rifle barrels from, and still manage to supply steel to the remainder of their war effort? While many M91/38's were made with standard twist rifling, there are enough out there with progressive twist rifling to indicate that, some time in 1940, the supply of steel for short rifle barrels dried up, and the old practice of cutting down M91 long rifle barrels was revived; much to the detriment of short rifle accuracy. This could also explain why the M91/38 short rifle was abandoned at the end of 1940, and replaced with the all "new" M91/41 long rifle.
As can be seen in the photo of C2766, the chamber of this famous M91/38 has also been machined smooth and round. The only way to tell if this rifle has standard twist rifling or cut down progressive twist rifling is to do a sulphur cast of the inside of the barrel at the muzzle.
Think they would lend us C2766 for the weekend?
Mr. HILL. The right rear portion of his head was missing. It was lying in the rear seat of the car. His brain was exposed. There was blood and bits of brain all over the entire rear portion of the car. Mrs. Kennedy was completely covered with blood. There was so much blood you could not tell if there had been any other wound or not, except for the one large gaping wound in the right rear portion of the head.
Warren Commission testimony of Secret Service Agent Clinton J. Hill, 1964
Warren Commission testimony of Secret Service Agent Clinton J. Hill, 1964