I am currently in the middle of a re17 vs H4350 vs superformance vs varget debate with my rifle. Also 165 or 180 bullets, haven't tried anything heavier or lighter. Also SST or GMX, also going to try TTSX.
So far, best is :
165 sst, 59.5 gn H4350 (compressed), 2950 fps, 1.25 group @ 200 meters
180 sst, 54 gn Re17, 2700 fps, no groups yet but this is the middle of the node
Superformance so far has been disappointing, but I have only tried the 165 sst. It is a denser ball powder, so it will take less case volume, and may be good for heavier\longer bullets. Pressure signs at lower velocities than I thought, and the ladder did not look promising at all.
Varget is next up, as well as some heavier bullets. The 180 gn sst ladder with re17 was impressive, i.e less than 2" vertical at 200 yards using between 51 and 55 grains.
These numbers come from a tight chambered Sako in 30-06. So tight that mag length is not an issue at all. I haven't blown myself up yet, but if you reload to these numbers, on your own head be it.