Both the 300 RUM and the 30-378 eat barrels. With 26" barrels, there isn't a lot of different in velocity between the two. The RUM has the advantage of no freebore, and relatively inexpensive brass. Also, RUMs are usually cut with tighter chambers since they headsapce off the shoulder.

Now in a custom gun, you can have a 30-378 cut with a tight chamber as well, though you might have to order a custom reamer. Typcially, chambers for belted magnums are cut with a lot of room in front of the shoulder, meaning the brass will flow around .018 to .025" on the first firing. With a 300 RUM, the brass will only have to flow around .003 to .005" on the first firing, meaning RUM brass ought to last longer.

Gus tell me they can get 3200 fps with 200 grain NABs, but I could never get either of my RUMS to shoot the Accubond accurately at those speeds. I also hear rgat 180 NABs will run 3300-3400 fps form a RUM.

I shoot a lot of heavier recoiling rifles. I can shoot my 416 remmy comfortable for many rounds, and was able to get an ocassional 1/2" group out of the 338 RUM I had. To me, an 8 lbs all up 338 Winny recoils rather mildly.

Having said that, I found I didn't like how my 8.5 lb 300 RUMs recoiled. Lots of snap and twsit. The 338 RUM generated more snap and push but twisted much less. I decided that the 300 RUM just wasn't worth the 200 fps it gave over the 300 Wby/ 300 Ack.

Some guys think that these big 30s are great 1000 yd guns when chambered in heavy rifles. They aren't. The recoil too much and wear out barrels to fast. I absolutely cleaned house with a 300 WSM shooting a 220 grain SMK in 1K BR competition. the short fat 30s to the 300 Winny still seem to be the 30 cal chamberings of choice in that game.