Which means, of course, that doubling m doubles K.E., while doubling V quadruples K.E. Because action is equal and opposite to reaction, no matter how you produce more K.E., the recoil is still proportional to the K.E. The K.E. released into the target depends on how much is left when the projectile flies out the opposite end, so because this doesn't happen in FH2 the K.E. released into the target is %100 what it started with, minus that lost to air resistance. Of course, if the shot flies out the opposite end of a tank, it released more than enough K.E. to do its job.
/nerd