Having looked at a number of charts on primer effect on velocity, the most I have seen has been equivalent to about a 4% change in the powder charge. I think if you just knock your load down 5% as a restart point, you'll be fine. Then load just 6 rounds, from 5% low back to your regular load in 1% increments to watch for pressure signs
. If you have a chronograph this gets easier because you just have to get to a velocity match with the same bullet and powder to be very close on pressure. Federal standard primers tend to be mild, so you may even find they let you use slightly more powder.