I will try several other types and weights in this rifle before staying w/ one.
Uhm.........Why?
Man I would be buying up every single box of those that were in that same lot number. To get a new rifle that will shoot 1/2 minute of angle and keep that kind of accuracy ar 300 yards, especially one with a huge powder capacity like the UM, doesn't come along every day. I'd say you found your load and in very short order.