the 30-378 is to most "magnum" cartridges what magnum cartridges are to standard ones. A horrible case of diminishing returns imo, burning between 25-40 percent more powder than the .300 weatherby for a 150 fps increase in velocity, at least out of standard length barrels with standard hunting weight bullets. This beast would be much more impressive with 30+ inch barrels shooting bullets 210 grains and up. I already observe in my .300 win mag a tendency toward non-linear gains when shooting heavy for caliber slugs...that is, it performs more efficiently with them. Its hard to make 150 grainers reach the same level of kinetic energy at the muzzle as can be readily attained with 200s. This will be all the more the case with this 30-378. Shooting light bullets out of cartridges with these case to bore ratios is like choosing to use a big truck with a huge v8 for everyday driving. It offers little or no advantage over a smaller vehicle with a smaller engine, where the big v8 serves any real purpose is pulling something heavy on hilly roads. To use it to go to the post office is kind of wasting its potential (and highly inneficient) So enough analogies and ranting, what Im saying is you'll likely have better results with the heaviest bullets you can load. One thing the reloading manuals should all spell out clearly is that cartridges of this size and case to bore ratio can be much more dangerous when underloaded than overloaded. Just as you wouldn't start out with an over-book-max load, do not under any circumstance try making "reduced" loads (under book min) - why anyone would want to do this with a .30-378 is beyond me anyways, but, it must be said, hangfires and detonations are a real possibility if you dont stay in the perscribed range. The slowest of powders are your friends. RL 25, H1000, H870, Retumbo, H50BMG, RL33. IMR7828 is probably way to fast a burn rate for optimal performance with this round (which is saying something).