Hey there, from Singapore here. Jus wanna let you know I'm really digging ur vids, very entertaining (and would also be educational, if not for my engineering and physics background, so already familiar with the principles here). Very refreshing to hear this in mandarin - I'm not very good at mandarin but can still nicely figure out what you are referring to. Physics is taught in English in Singapore. Could you explain why it seems that in all cases a capacitor would discharge sufficiently once the bullet has shot past it, and not hold excess charge to attract the bullet backwards? Can it be proven so for all cases, or you just happened to get it calibrated that way?
