Hard is... well hard

I easily beat all scenerios with an S or A rank on Normal... now I'm going through trying to get an S rank on Hard. I've managed to easily get S rank in "Train Derailment" and "Mansion Incident" along with their respective extra scenerios with Wesker/Rebecca. Not a problem. However, Jill/Carlos's first level is giving me some trouble. It's just so stinkin long and zombies love to run up to the screen and swipe before I can headshot them. Bah, I say, bah! I got an S rank for the last 2 Racoon's Destruction levels and Ada/Hunk's missions. Piece of cake.

I figured the last scenerio would be easy since it's so short... WRONG. I got S rank with Wesker's side scenerios, but the Chris/Jill portion eludes me with a respectable, A rank. I keep getting C rank in time for the last Chris/Jill mission under the Fall of Umbrella... Any pointers? I'm not slow, hahaha but I don't know why I get a C rank. I get an S for objects destroyed, A or S for critical shots, S for files, A or B for enemies killed but a stinking C for time... what's up with that?

P.S. I know the other ranks don't determine time's rank... I was just saying.

Well... now the game's kinda done... I just unlocked infinity ammo upgrade option after beating all levels with S rank on hard... Nothing left to do but go back and actually TRY to find all the files.

I don't find time to be that difficult at all. I get S when I don't really try to. The trick to the level I was stuck on was to not try to get the extra anti-tank rocket in the weapon room. Just take the quickest path to TALOS.