Mid- for shooting whitetail at 500 yards or less a 150, 155 scenar, 167 scenar, 168 berger or 168 cbt will be just fine. for your intended purpose, they are faster, flatter, and kick less than the long heavy ones mentioned by others . try loading them .030 off the lands. for other powders I would start with varget. my go to load is 50.4 varget, lapua brass and a 210m. the projectile could be a 167 scenar, 168 cbt , 168 berger . or one of several other 165-168 bullets. sounds like you have a good trigger. I did not see what scope you were using if it was mentioned.