Related Clues:

• Gun shop stock
• Guns' partner
• Snowballs, at times
• 'Bullets'
• Barrel filler
• Peas, for pea shooters
• Munitions, slangily
• Firing range rounds
• It's effective only when fired
• Magazine pieces?
• What some chambers hold
• Armory holdings
• Stuff in a barrel?
• GI's supply
• Bullets, say, in short