I believe the little plastic cup is intended to keep odds and ends accounted for when doing maintenance. Which is very odd, since no part of the gun save the locking block will fit in that 'lil cup. I use mine as a thumbtack holder on my desk.
My dad carried a Beretta 96 as a cop for about ten years, and he was amazed when he could do much more rapid followup shots with a gun about 1/3 lighter.
14 Pistols, 5 Rifles, 1 Shotgun, no time to shoot them