Overall, great blaster. Here are a few problems that can be solved for little to no cost:
The pump grip can either be replaced for a 3D printed grip, or it can be reversed (unscrew it and put it back on with the lip to the back). This costs nothing and feels so much better.
The stock is sorta shaky, and so you can take it off and put a few strips of electrical tape on the top. You should be able to still move the stock around, but it is very sturdy.
Put a rubber band through the two pins because they are really annoying when they bang around.
Other than that, I really have no complaints.