To dry fire open the back and then use your finger to roll the film counter past 1 or 2 hold it there and close the back, wind and fire all you like. A dud roll will not stop you being a klutz a breaking sometime though. If you just want to check the film flange distance open the back and measure the distance between the pressure plate and camera back then measure the flange to back and subtract that measurement, won't need to stick thing into the camera unless its for pleasure