- .17 HMR
- .22 Hornet
- .22 Long Rifle Ammunition
- .22 Short Ammunition
- .22 Winchester Magnum Rimfire (WMR)
- Accidental Discharge
- Accuracy
- ACP (Automatic Colt Pistol)
- Action
- Air Space
- Airgun
- Ammunition
- Animal-Gut Cartridge
- Annular Ring
- Annulus
- Antimony
- Anvil
- Armor Piercing (Ammunition)
- Attached Head
- Auto
- Back Bore
- Backthrust
- Ballistic Coefficient
- Ballistics
- Damascus Barrels
- Gauge
- Second Amendment