I wouldn’t say Swamp’s numbers are far off the mark. The RUM with 250 gr loads with +.700 BC started at 2,850 fps does yield about 2,750 ft-lbs at 500 yards. Depending if you start the 30-06 with 180 gr at 2,750 fps you’d get around 3,000 ft-lbs at the muzzle.
At 900 yds the RUM will maintain around 1,750 ft-lbs, that’s right about where the 06 is at 400 yds with a 180 gr load.
Comparing just the energy of a 250 grain out of a .300 RUM vs 180 grain out of a .30-06 at those distances may very well be comparable.....I dunno.....but using the same bullets the velocity and energy math doesn't add up.
