1500 Armex Hardball Air Rifle Pistol Airgun Gun Steel .177 BB Ammo Pellets Balls Supplied in a handy reusable bottle. Armex Hardball .177 Steel BB’s – 1500 Pack (approx). Weight: 5.4 Grains. IMPORTANT Info: These BB’s are not plastic and will ONLY WORK in airguns designed for steel BB’s. The manufacturers describe the BB’s as 4.5mm but when measured with a digital caliper they are 4.4mm diameter. They will be NO USE in soft air guns or airguns designed for lead pellets or lead BB’s.