I have a few of these rifles in this caliber, , some stock, some built up a little and a full blown custom built rifle, the 300 RUM is a very accurate caliber
things you can do to make it more accurate is, trigger job, sure, better stock SURE, all the more so when bedded right
re corun the muzzle
have the action trued up
all rather simple things any GOOD smith can do for you
can also lap the bore if there is need for it
but also a BIG part of accuracy is just finding a load the rifle likes