The 7AM with a 200 grain bullet and the 30-378 with a 240 SMK are very similar if similar barrels and reloading techniques are used. Both will perform better with a longer barrel than 26 inches. The problem is as Brian Litz has described, the 30 caliber just doesn't have a really good long range bullet. The 240 SMK is a fat dog wallowing through the air. It needs a better ogive shape
I spent a lot of time trying to decide between a custom 30-378 and a custom 7AM being as I am a big Weatherby fan and a big 7mm fan. It was hard to decide. If both are custom rifles
it is a hard decision but comparing a custom 7AM against a factory 30-378 the needle points to the custom rifle
because of accuracy.
There were a few reports of some good aluminum tipped bullets in 30 cal but it was hard to verify the credibility of the reports ( and that is putting it mildly).