I have a couple tanks approaching 3 years old. All the cheap screws wore out and were replaced with quality SS ones from my local hardware store. All the holes are fine. Like Slotcsx says, screwing the tank together is necessary to strengthen it.

Wait, I remember that some of the holes on the bottom of my M26A1(oldest tank) turret stripped out. I filled them with wood putty filler, let it dry, drilled a new hole down the middle and then screwed it together again. Been apart a few times since no problems.