I agree that the wapons seem a bit.... ..wussish, but this is not because of the alien's "response" to being hit, its rather the sounds (they need more bass, they are to sharp to sound forceful enough for my weapon taste)
also, the guns need some more animating, not like moving parts of the gun, only moving the gun as you shoot, like a machinegun shaking slightly in your hands as you shoot or the shotgun getting a kickback in your hands in a more "persuasive" way.
i mean, the guns there are now, are just too steady, the only real weapon that would have this little recoil or so is the small, shitty guns, or the wussily high- tech ones.
What we want is more badass, dirty guns made of rough steel.
if you didnt care to read all this, here is a summary.
I want a small texture change, i could possibly do this myself by editing the existing ones, but i'd probably give up.
I want some changes in weapon animation while firing, for more natural gun recoil.
And last, but not least, iwant other sounds with more bass, with a bit more "thud" to it. look to enemy territory for a good example.