Mike Hill

Mike I do believe that primers can effect accuracy. The amount if heat applied to the charge will begin the burning of the powder. The more fire the a larger amount of powder ignited - the faster the spike occurs. There is a difference in velocity from very hot 209's down to cool 209's.
If you change from one brand of 209 to a different brand but they are in about the same heat range the accuracy should not suffer.

Just my 2 bits again