hey Huvius:
Didn't realize you had one of the few remaining Harris patent Lee Speeds too, they're a fairly rare variant by all accounts.
Also known as Punchard's magazine filler for some reason that I have been unable to determine (if you can shed any light...?)
Certainly works beautifully on the 1905 Ross, makes me want to start looking for one!

Apologies for minor thread hijack, back to the .405.
Without something equivalent to the Harris (Punchard) filler, rim discipline would not be something you could count on IMHO, especially in the hunting field, and under recoil.
Personally I would not trust rimmed cartridges in a straight mag box M98.
...in agreement with most everyone here by the looks!

Edited: My ailing memory Huvius, apologies!
We had a discussion about these Lee Speeds over a decade ago. Did you ever toss photos of yours up on the forums?
Here's the link to my example. Might be of some interest here given the usefulness of the Harris Patent for rimmed cartridges.