IMO, the 300RUM is one of the most difficult rilfes to get to shoot consistent MOA. I have shot out 3 barrels target shooting with them. The huge 0.25-0.4" jump to the lands makes it difficult. So about 10 years ago, I had a custom throat where you could hit the lands within 3.6" max COL with 180gr accubonds with .9" kreiger barrel with mcmillian stock. Big mistake. Kinda. It shot damn good, but all reloading data went out the window. My tried and true 94gr of H1000 now had huge pressure signs. Instead of getting 3300fp with 180gr pill, I was getting 3100fps. I can almost do this with 300 win mag, and lot less powder. I shot it for 800 rounds, and started getting heat cracks in the throat.
I have since moved to 300win mag, and no regrets.