Depends on a few things, mostly the action. If your rifle is a Dakota M76 then the action is likely "standard" length, which means magnum length cartridges with .545" head diameter such as the .404 Jeffery will not fit in the magazine box. You're limited to cartridges like the 300, 330, 375 Dakota. BTW, the 7mm Dakota is a great cartridge, one of my favorites - I like it better than the 7mm Mashburn (grin).
If, on the other hand your action is "magnum" length with a full length magazine box consider the .375/404 that the guys over on AR like so much.
