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More Ballistics


John Ritchson
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[Leo Segoros Wrote:]

Please pardon me for butting in Someone made the statement that nothing that happens in the barrel affects the bullet once it achieves velocity. Not true. The number of "twists" in the barrel matters on the bullet. When the M-16 first came out it had a 1 in 14" twist barrel. The bullet was understabilized and deadly-modern M-16s have 1 in 7" twist, a super-stabilized bullet designed to penetrate Soviet body armor. What happens in the barrel has everything to do with it Leo

Greetings, somehow my post addressing this got lost in the mail so I'll repost. You made a very good point here which shows you have a better grasp of the subject matter than Mr. Burke would have on his best day. Proper twist is an absolute requirement for bullet stability leading to down range accuracy. Heavier,(longer) bullets need a faster twist for in flight stability and smaller lighter bullets require a slower twist. When the M38 Carcano was first developed, it was chambered for a 7.35mm cartridge which was the same case as the 6.5mm but with the neck expanded to accomodate the larger 7.35mm bullet. The 7.35mm barrel was cut for a 1 in 10 turn twist which was just fine for this bullet. However, and here is the problem, sometime around the beginning of WWII, the Italians decided not to proceed with the retooling for the 7.35mm and instead went back to the 6.5mm bullet. Now the origional 6.5mm barrels on the model 91 Carcanos were cut with a progressive or gain twist starting with a 1 in 19" turn at the breech and ending with a 1 in 8" turn twist at the muzzle. Such barrels are far superior IMO, to a standard cut barrel which is why I think the Italian National shooting team still uses the M91s in competition match shooting, but when the M38 Carcanos were rebarreled to 6.5mm, only a very few were rebarreled with a gain twist barrel, probably only until what existing stock left was used up, and the rest composing the vast majority of all M38 Carcanos ever made were fitted with standard rifled barrels which unless the gun factories retooled their groove cutters to the faster 1 in 7" turn twist which is optimum for the 6.5mm bullet, would have been the slower 1 in 81/2" to 1 in 10" turn twist, and I have seen no evidence that such retooling ever took place. At any rate, this snafu with respect to the production of this rifle is just one more reason why the M38 Carcano, with the possible exception of the Japanese Arisaka, is concidered by many in my trade to be the worst rifle ever made, and all the LNers can say about it is it was good enough to do the job which has got to be the weakest arguement I've ever heard.

Equipped with this rifle, a shooter of the caliber of LHO on his best day couldn't have hit the water if he jumped from a boat, much less accomplish what the WC said he did.

With Regard,

John Ritchson :ph34r:

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