This is in the gun's server.cs, it's what is responsible for the recoil animation.
function gunImage::onFire(%this,%obj,%slot)
{
Parent::onFire(%this,%obj,%slot);
%obj.playThread(2, shiftAway);
}
%obj.playThread(2, shiftAway); is what is responsible for playing the animation, you can comment it out (put two slashes behind it) and it will not play.
You could even delete the whole function and it won't matter, just don't take the Parent::onFire out or things will break.