That is seated too deep for that load. Also My max is 52 with a 130 @ .020 off the lands. At .050 you are seated down into the case I believe. I have the same make/model rifle. H4350 works pretty well. RL17 works even better for me, and h4831sc always works with this cartridge if you are just chasing sheer accuracy. If you are trying to shoot a really long ways RL17 will get you the velocity you are after while keeping the accuracy. Mine likes .010-.020 off lands. I use 130s but it works with 140s just as well for accuracy. Just the 130 has less drop inside 600 yards if I remember correctly because of the velocity gain.
Not sure what Hornady manual your getting data from but #8 and #9 have max loads of 47.2gr/N165 with their 140gr bullets as max load. That data is for the 6.5x284 COL 2.880" not the 6.5x284 Norma COL 3.310" and if your going to use Hodgdon data it's also for the 6.5x284.