AmmoSgt
Posts: 1002
Joined: 10/21/2000 From: Redstone Arsenal Al Status: offline
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A couple of thoughts on smoothbore v rifled bore. Rifleing in a gun can only optimally stabalize bullet weights within a certain weight range .. now days, tank, ammo is so specialized and uses such different mechanisms to defeat armor that keeping all ammo types within that range would not allow for the specialzation needed .. The other major reason is Velocity .. rifling can really eat up velocity( slow the bullet down by creating friction and converting some of the energy into spin) .. or the ultra high velocity on APFSDS type ammo would really eat up the rifling , quickly making the gun inaccurate. It is much easier technology wise to just use a smoothbore and design the ammo to use other stabilazation methods the "FS" in APFSDS stands for "fin stabilized" . As noted above spin does reduce the effectiveness of HEAT ammo by the centrifical force pulling outward on the Monroe effect jet that is the penetrator action of HEAT Ammo. HESH is not effected that much by spin as I understand the action of that warhead.. and if you notice many rifled cannons have HESH , but I don't think many smoothbores have HESH. A long slender APFSDS round out of a 120mm smoothbore is designed to be very light( in comparison to a HE round of the same caliber) .. maybe 30 pounds , often less, so you can achieve the ultra high velocites , approaching 6000 fps to take maximum advantage of the Force= mass x velocity squared equation, pure kenetic energy does the work. With chemical energy bullets that use High Explosive to do the work on the target HEAT, HESH, HE and the like you want the maximum weight of explosive .. with a 120mm Gun you can squeeze 60-90 lbs of explosive in a bullet .. However if you tried to fire a 60-90 lb solid shot ( like APFSDS) at 6000 fps the chamber pressure would be so high that the breech and barrel would have to be so thick and strong to contain it it would be hard to fit it all in a tank weighting twice what a M-1 weighs. So .. what you do is fire really "light", in comparison, solid shot at very high speeds and chemical energy rounds that are much heavier at lower speeds .. chamber pressures stay within bounds .. and each type of ammo gets to do the job using different methods to the best advantage. And your barrel lasts longer.
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"For Americans war is almost all of the time a nuisance, and military skill is a luxury like Mah-jongg. But when the issue is brought home to them, war becomes as important, for the necessary periods, as business or sport. And it is hard to decide which
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