PLEASE ADD A DOWNSIDE THAT DOESN'T INVOLVE AMMO OR HEATH I CAN'T TAKE IT ANY MORE (minor exaggeration of my feelings for comedy)
Some ways to to this is a tweak that deals less or no damage to start but does more damage then a base shot a second or so later. I based this idea off of poison so you could just do that instead if your* boring.
Another downside is if you added a range limit to weapons which could be interesting while definitely being better for some weapons then others.
Something else that could be done is that less damage is delt overall but a vulnerability effect is applied that amplifies damage**.
One last thing, if a dev reads this I would appreciate feedback on my ideas as I am always looking to improve.
*grammar is for the weak
**this could only apply to your damage or both you and your teammates, depends on the % of damage amplified.