Casey,
Yes, I feel much better that you're going to disassemble your potential frag grenades! (perhaps over-stated, but none the less a wise decision in my opinion)
When shopping for powder for your .444, RL-7 as you have mentioned and H335 are top picks, along with H322. These powders will deliver both velocity and pressures within the working realm of reasonable for your Winchester 94BB.
Too, I've heard of others with the same difficulties concerning wide meplat bullets and COL in regard to the loading gates and "bending the corner" into the magazine tube.
Let us know what you find and how your gun shoots once you get some powder!
Thanks for the update!
God Bless,
Marshall