What are FMJ "ball", ammo cartridges intended for use in pistol calibers? Wikipedia says: "The use of full metal jacketing in military ammunition came about because of the need for improved feeding characteristics in small arms using internal mechanical manipulation of the cartridge to chamber rounds as opposed to externally hand-reloading single-shot firearms. The harder gilding was less prone to deformation than softer exposed lead, which improved feeding." I was always under the assumption they were mostly used for plunking at the range. The reason why I ask is, I'm considering carrying them in a concealed carry instead of the more popular hollow point type cartridge.