Patience daniel-son
Well, it looks like a lot of people aren't as familiar with the firing mechanism of a painball gun as you are, myself included.
Thinking of the original circuit, I'm sure that the manufacturer designed it minimally in the first place. Reducing the circuit even more might require some hard core engineering. Maybe not, I'm not sure. The question that comes to mind is "The manufacturer designed the system purposefully to be efficient both in cost, and function in the first place. Without understanding the original circuit, how can we improve?"
Thus, I believe if you/we are going to come up with a better idea, it would begin with having a full understanding of the original circuit. Thus, we can better understand the works behind the mechanism. With understanding, we have better opportunity to improve the system.
With that said, Would you happen to have a cricuit diagram for this circuit?