How much gain is there comparing the 338 RUM to the 338 Win Mag? My reloading books are so old they don't show the RUM rounds and I don't have a reliable source to compare to- besides the experienced loader/shooters on this forum.

For comparison, let's say with a 225 Partition or Hornady spire point.

Thanks,
Bob

Never underestimate your ability to overestimate your ability.