Hint: 255 grenades:
Change your weapon to the grenades and hold Z until the throw meter is filled .When the grenade is being thrown, hold Z again until the meter is full. Repeat until you are on the last grenade. When it is thrown, you will have 255 grenades. Note: This trick can be done with regular or flashbang grenades.

Hint: Disable flashbang effect: Use the nightvision goggles after getting hit with a flashbang grenade to quickly restore your sight.