Any idea why a light charge, with too much OAL would cause a round that recoils worse than 158gr +P factory ammo?
According to Alliant's site, 5.3 gr of Power Pistol under a 146 gr JHP is a recipe for a +P load.
Alliant lists 5.5 gr. as the max for that +P load.
What you assumed to be a light load is in effect in the over pressure catagory.