Explanation of a muzzle Brake or Compensator
http://www.cruffler.com/trivia-May01.html
Early recoiless rifles used a counterweight ejected rearward .. but it was quickly found that that was unnecesary due to F=MV2 (Force equals mass times velocity squared) by talioring the rearward exhaust gasses so thier higher velocity compensated for their lack of weight you basicilly eject the same force in both direction, one of large mass at a low speed forward ( comparably) and a low mass ( weight of the gas )at high velocity The gasses rearward, it works because the velocity is being squared . You use a venturi tube shape to basically compress and accelerate the gasses to achieve the velocity , not unlike a rocket motor exhaust bell. Your do loose some forward velocity simply because you have to use lower pressures over a longer time .. however the lower pressures also mean you can use a thinner gun tube so you save even more weight. Downside is a high errosion rate on the metal of the weapon. Upside is a lower muzzle velocity makes designing the fuze system for a HEAT Round easier since you do not need as fast of a fuse. Downside is you have to use rifling to spin the shell for stablity because fins or vanes just burn up , and spin acts against the shaped charge effect making it harder to form the plasma jet . French CN series Cannon use a ballbearing obturator bands on the shell itself to spin at a regular speed as gyroscopes while the shell itself spins much slower from the reduced friction vetween the obtirator bans ( the parts that engae the rifling ) and shell seperated by the ball bearing . In a normal shell the obturator bands are fixed to the shell ( Look at a regular artillery shell or tank gun bullet closely and you will see two raised surfaces around the shell .. near the rear a band of soft metal , usually brass, that engaes the rifling, and near the front of the full diameter part a slight hump of hard metal that rides on the tube lands. In rifle bullets the copper jacket itself engages the rifling ).
US HEAT Ammo uses vanes inside the cone to counterspin or de-spin the plasma jet basically ,( poor explanation for a more complicated process). Any shell spin creates an outward centrifical force that wants to break up the plasma jet, so you have to compensate for it somehow.
The lower velocity on a RR type gun is fine for any warhead using chemical energy, HE or HEAT with just a reduction in range, but it really hurts kinetic energy rounds that derive their energy from the velocity F=MV squared again.
"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
