what does fmj ammunition mean
A full metal jacket (FMJ) bullet is a small-arms projectile consisting of a soft core (often lead) encased in a shell of harder metal, such as gilding metal, cupronickel, or less commonly a steel alloy. In military nomenclature, it is often labelled Ball ammunition.t also prevents damage to bores from steel or armor-piercing core materials. Historically, the first successful full metal jacket rifle bullets were invented by Lt. Col. Eduard Rubin of the Swiss Army in 1882.