With a 45 acp revolver, loading for function is the main thing. Some semi-wadcutters will hang up on the cylinder throats if seated too long. Some bullets may not have enough case tension to prevent pulling under recoil if not seated deep enough. Within a range of proper functioning, I've not found much accuracy difference from reasonable seating depth variations. Depending on the dies used, it can be a problem getting enough case tension with lighter .451" bullets. An undersize sizer is nice to have when loading .45 auto for revolvers.