Many people ask me about loading for the 338 RUM since I worked with it quite a bit at my range back in 2001 when it came out. So I decided to put up the best loads I have found for it. 300 grain SMK- 92 grains of H-1000 and 95 grains of Retumbo are on average about where you will end up as the best loads. With 28 and 30 inch barrels they average a little over 2800 fps. I have not tried any new batches of H-1000 so wouldn't know about some people claiming the burn rate is now different and they have to go down on their loads. My loads are with the old H-1000. Start 2-3 grains below this and work up. 225 Accubond- 97-98.5 grains of RE-25 is the best I have found. Velocity will average around 3200 fps to near 3300 fps in some rifles. I tried the 265 Barnes and got exceptional results with it. The BC with it and some other Barnes bullets I worked with seem to be higher than listed. It is extremely accurate at long range shooting and is easily capable of making hits well beyond the range capability of most shooters. This is a huge plus since it is a fantastic premium hunting bullet. Accuracy loads hit between 2900 and 3000 fps out of a 26" barrel with H-1000 and Retumbo. Some loads went over 3000 fps. These were only tested in my remington 700 factory rifle. H-1000 from 94-96 grains and Retumbo from 96.5-99 grains shot very well in this rifle. Since this is the only rifle I have shot these loads in just start at my low end and work up in your rifle. The Barnes shot best off the lands which is where I shoot all my Barnes bullets. Hope this helps some guys with this cartridge.