Re: 25-06 Ackley Imp or 280 Ackley Imp?
I concur with Why not's advice about trying AR2213sc(H4831sc) and Reloader 22 with the 100 grain bullet.
I would be extremely surprised if you could find surplus WC 852 here in Oz. The Alliant range is now available here,and the importers are advertising in the latest Shooters Journal, so you could contact them regarding sourcing some Reloader 22 (and Reloader 25 if you want to use the 115/120 grain or heavier bullets.
Also, as Why not suggests work up carefully with each powder and focus on pressure rather than trying to specifically achieve 3,700 fps. In my first 25/06AI, I achieved 3650 - 3700 fps with the 24 inch barrel, but discovered that cases only lasted 3 - 4 shots before primer pockets loosened. In rifle 2, which also has a 24 inch barrel, I have found that at about 3,550 fps with the appropriate powders, I get between 7 - 10 reloads for each case.
Estimating velocities in a different rifle is near impossible, as chamber dimensions and other variables come into play.
However, if your load of 60 grains AR 2213sc with the Nosler 85BT was fired in my rifle, it would be a vary mild load and velocity would be way down. The load of 62.0 grains/AR 2213sc was maximum in my rifle with the 100 grain BT, and the load of 60.0 grains produced 3344 fps. So it would probably take at least 64.0 grains of AR 2213sc to get near maximum with the 85 grain bullet, and my case only takes about 63.5 grains of that powder to fill to the base of the neck.
Personally if I was going to use the 85 grain bullet, I would use a faster burning powder than AR2213sc if you are trying to get maximum velocity. I suggest AR 2209(H4350) or Reloader 19 as ones to try.
It may be of interest to you, but last week I tested Richard Graves 130 and 142 grain Wildcat bullets. I found that the 130 grain bonded core produced very good accuracy (best group .185) and velocities up to 3,150 fps. The 142 grain ULD failed to stabilise, and produced velocities up to 3,050 fps. Good luck, Brian.