I don’t know how big the pin holes are that you guys are trying to fill, I have always used an inexpensive product called 3M Acryl-Green Spot Putty product number 051144-05960 with good success.

Apply it with just a soft plastic squeegy, it dries fast and sand with 600 wet paper, prime and sand and paint, and wala! pin holes bye bye! This is my 10 centavos worth.