PD may stand for Pulled Down, as in powder salvaged from military ammo pulled apart for components. I have used many kegs and jugs of PD powder over the years. If pulled down powder, start low and work up. If in good condition, pulled down powder is nice and saves you some money.
When I googled 4895 PD powder, IMR is what came up but I figured since I don't know anything about it, it must be harder than that to come up with the answer.