I have noticed that even if you upgrade a weapon's damage, the amount of damage doesn't change. Not in the statistics (impact) or in the amount of damage produce with each shot. For example, I've got a Legendary Auto Rifle called the "Unwilling Soul-09." When I got it, it was doing 35 damage in body shots, and 72 damage in critical shots. Now I've got the first two damage upgrades on it, and it's doing the exact same amount of damage to the exact same characters. What gives?