Re: 338 ulta verses 338 kt mag
I just received a new Remington 700 Sendero with a 26" barrel in the 338 Ultra Mag. I have tried three different powders to date Rel 25, H1000 and H870 with the Sierra 300 grain MK. The average high velocities from safe loads have been from 2565 fps with H870 to 2688 fps with both Rl25 and H1000. These are not hot loads in this rifle. All three powders have shot the 300 MK into groups from .458" to .800" at 100 yards. This rifle is very accurate but it does have heavy recoil. This weekend I will work up loads with the 250 Sierra and the 210 Nosler.
My son and I shot accross the canyon out to 910 yards with the 338 Ultra this past Sunday. Ranges were from 620 to 910 yards with the 300 MK. The 338 Ultra hits a whole lot harder than my 300 Win Mag. The 338 Ultra had no problem at these distances using the ballistic data spreadsheet that Peter Crohelm (sp?) and Dave King have developed. This spreadsheet calculates that the 300 MK with a BC of .768 and started at 2650 fps, at an altitude of 8800', has 2408 lbs/ft of energy at 1000 yards.
I am not familiar with the 338 kt so I can't comment on the comparision between the two. I am happy with the 338 Ultra. Hope this helped you a little.