we had a similar gun in the 70’s in northern nj but we used many
rubberbands(the more the deadlier the sting) and
we nailed a spring clothing pin to hold the rubberbands and projectile. we even fashioned them to look like machineguns. at times we even had double barrel guns by using two or even 3 pins. after a few years
of this during the summer, the weapons were becoming to powerful and the projectile of choice became the round part that soda and beer cans had when you open them. they would be all over the ground in those days since they detached when a can was opened. soon after our parents banned our weapons. we destroyed most and hid some–never to be used again.