[snowman]

I meant 0.003", not 0.0005". You probably need to heat the hole, freeze the pin and use a 5 ton press to fit the pin, and yes it needs tapering on the leading edge. The materials are important. If the coefficient of expansion of one material is 3 times that of the other, its very important.

One example is a valve seat in a aluminum head. The valve seat may have an expansion rate of 6ppm/deg C and Al 22 ppm/deg C. You better have at least a 0.003" interference fit or the seat will fall out. For larger holes, like a cylinder sleve in a 4" bore, you may need 0.005" to 0.008" interference and thats for a steel sleeve in a cast iron bore.

Materials, operating temp range, and stress conditions are all important so there is not a single good answer to your question, but only 0.0005" for a 0.3" dia is marginal.