Brass Enclosed Base (BEB) ammo meets indoor shooters' needs, being the reverse of a full metal jacket. The front part of BEB bullets have exposed lead, and since the lead is away from the ignition source, lead particles in the air are reduced. Though rarely an issue, their downside is the potential to jam in semiautomatic weapons as a result of the indentation on the bullet’s nose where lead is exposed. Here is our in depth article on BEB ammo.