>>285143838
bullet reservoir was the most useful upgrade, followed by the grenade launcher because it was basically a free backpack slot
burst ate up too much ammo on hard, usually wasted at least a bullet or two so I switched it off
there was only a single setpiece in the whole game where the shotgun auto-loader came into play
double-shot can take heaves down .5 seconds faster, I guess?
and the rest of the upgrades just help you aim