Good question. The difference is about 100 fps with bullets up to 200 grains. The 338-06 would have the edge with the 200-250 grain bullets and is not far behind the 338 Win Mag. The 338 Federal may not fly but the trend toward short certridges may help it out. It will have to appear in a less expensive rifle to make any splash at all. The 338-06 is a very good cartridge and deserved better treatment than it got. Everything based on the 308 case has done pretty well. Of course the 308 case was just a shortened 30-06 case.