shootn hogs,

Sometimes a rifle just does not like a particular type of bullet. I had a .300 Winchester Magnum that I was bound and determined to shoot Hornady 190 grain Boat Tail Spire Points out of. I tried 3 or 4 different powders, different primers, different brass, different seating depths etc. Went through a whole lot of bullets and powder before I gave up. Tried the 180 grain version of the same bullet and within a few experimental groups I was onto a load that would shoot accurately and consistently.

With the information you have given I would be tempted to say your Sendero doesn't like that bullet. Maybe buy a box of Nosler ballistic tips and see what happens with them.