See how you go with this. I'm using whatever version is available as of 29th April 2017.
You should set the lock on the cheats once you've started a game and loaded it. Max money on screen is 9,999, anymore than that and you can't pick more up, usually. I've set it to $100,000 and put that in the bank, then given myself more. Be careful picking up hats, and buying hats, the game doesn't like it. This game is less stable than a 1 legged, drunk 4 year old during an earth quake. Be prepared for crashes.
Infinite ammo only works on the Pistol / Dual pistol. The shotgun and rifle were just too hard for me to work out.
An update... After wanting to learn how to do scripted cheats, I put some effort in today and watched a few Youtube videos, played around with some games and thought I'd come back to this one. I managed to get the cheats working via an aobscan script.
There is one caveat! This is a compiled flash game, which usually means JIT compilation (Just In Time). The concept being that until a section of the code is required, it does not exist. So in order for the scripts to work, you have to 'trigger' them. This means losing a life, picking up or spending money and shooting your pistol at least once.
The upside? The game is far far more stable using the scripts rather than the old cheats. I've tested this on the two characters I've unlocked, and it worked well enough. Any issues let me know and I'll pretend I know what I'm doing when I try to help.
Infinite Ammo - Pistol / Dual Pistol
Infinite Money (You get 9,999 if you spend some)