Yes, the 'two guns' is good in the end, not so much in the beginning, that's why I blocked it until the wave 5.
Try to shoot the exact amount is probably the safest (and overall better) strategy, that's why I used mostly odd numbers! :p
The bullet in the wall is a bug I tried to fix it but couldn't find a way to do it in time.
I'm glad that you liked playing! Thank you for the feedback! :D