I never really ran out of ammo but there were times i was down to just a few clips with the handgun and some rifle shots, but healing items on the other hand....i walked out of the last battle with 4 first aid sprays, 4 red/green herbs and 2 red/green/yellow (life was at max) on my first play through.
If i would change anything about this game it would be the difficulty of puzzles, I never really had to think about any of em.
Real shooters always aim for the head.