Introduction: K'nex SMG.
This time, it shoots. Also, added stock for performance. Pretty simple design, and you want to use as many bands as you can on the ram rod. If anyone wants me to post, (even though I bet you could build it from the pictures,) let me know and I will. Shoots gray connectors.
easy to use
SOMETIMES fires two at once
occasionally ammo gets stuck in the barrel, but more bands will fix this.
Not so amazing design, you probably have seen something similar to this before.