Re: 300 RUM elk loads
My experience on elk is like Wyo's, you need a tough bullet and as big a caliber as you can shoot accurately. I found when I went from the '06 to the .338 magnum that the elk went down faster, as in fewer shots.
Suggest elk are justification for premium bullets, there are lots of them. Nosler's new Bonded Ballistic Tip is intended for big magnums (200 gr.) and then there are Sciroccos, Trophy Bonded, A-Frame, Partitions, Barnes, Grand Slams, Bonded Coreloks, Failsafes and the new Hornady Interbond for instance (also a new bullet called the Groove). Hard to beat the good old Nosler Partitions for elk, but any of these bullets would be a better choice than Ballistic Tips. Wyo is typical of elk guides who see how tough the critter really can be - there are perfect scenarios where the animal drops like a stone, and others where you really need penetration and power.
I do not believe that there is anything wrong with 3/4" accuracy from a factory-built Ultramag, that is good shooting on your part.