Unfortunately your problem has been reported by a number of M94-357 Magnum owners.
With the rifle unloaded, open your action just enough to slide the bolt back but not enough to raise the carrier. When the lever comes up there is an additional small spring on the lever which helps to hold the cartridge at a horizontal position and to prevent it from sliding back under the carrier.
With the lever down and the bolt back look around for this spring, you may or may not be able to see it at this point. If you cannot see it, move the lever the last little bit and raise the carrier. Look at the carrier where the lever comes up through it and look forward of this looking for a small bent flat spring.
I have seen two of these springs bent over and allowing the cartridge to slip past.
If you handload make up a few action dummies and put one in the magazine. Working the action slowly watch the rim and see where it is stopped.
Once you locate the spring it is pretty obvious how it works. It is hard to see it and many people do not know it is there.
Incidentally, when working properly this may be the most fun of all the Model 94�s to play with.
My fathers 357 Trapper feeds anything with the rifle at any angle.
