I'll throw it out there. A 203 shell with BB's inside and piece of napkin or tissue paper stuffed in at the top.
Just the 203 shell, nothing else. Actuate your "secondary" by pressing the button on the back. :P
Or at most the S-Thunder Flaregun/pistol thing, but you won't be as high speed/low pro as people who run only the shell.
ಠ_ಠLess QQ more Pew Pew
READY TO >> RACE