The Ammo

Grenades

5 per ball

Used bare handed or in a grenade launcher

It ends up looking like one of these:

Ammo Usage

1 grenade per throw or shot

The Damage

Grenades	125	Blast Radius Range: 165 Game Units
Grenade launcher	120	Blast Radius Range: 160 Game Units

Firing speed

About 1 per second

Range and Accuracy

Grenades travel in a sharp arc towards the crosshair. They'll bounce until detonation (about 3 seconds after they're primed).
Grenades also offer a large radius damage effect when they explode. With the hand held grenades, holding down the trigger will allow you to throw the explosive farther. Holding down the trigger without releasing the grenade for more than three seconds will cause the weapon to detonate in your hand.

Attack

The grenades are best used in retreat or around corners where an enemy's location is known. Grenades should never be used to chase a fleeing enemy down as the shooter will probably be running right over loose grenades just as they detonate making it very likely for the player to kill himself.

Defense

The best way to fight a player launching grenades is to not pursue, but find another way around the map to maneuver behind the opponent - most maps allow the rooms to be entered from more than one direction.

Extra Info

The launcher fires more quickly than the hand thrown grenade, and will never detonate while holding onto it but each grenade does slightly less damage than when they are thrown.
Any grenade (launched or thrown) will detonate instantly upon colliding with a player or enemy.