Just how much are you priming it and how? What method? Are you pouring fuel in the carb or choking it and drawing fuel through the fuel line?

I find best results when (with glow heater off) I open carb fully and put my thumb over the intake. I then run the prop through by hand until the fuel from the tank reaches the carb inlet nipple. I then give it 2 more flips. Close the throttle to just a little above idle setting. Apply plug heat, wait a few seconds for the plug to heat up (3 is usually plenty) and apply the starter.
Should now be running.

Are you hurting the engine? Probably not but remember the oil is in the fuel so never turn it over dry. Proper tuning is also important.