The Rizzini uses standard 444 Marlin barrels which are 1/38" twist.
The double is regulated for the Hornady 265 LeveRevolution ammo so I haven't done much with 300's in it.
I have calculated, using the Miller twist formula, that as little as a 1/30" twist would take care of most any 44 bullet and stability of the longer bullets would no longer be an issue.
The newer 444's with 1/20" twist (and "normal" rifling) I think is a little overkill in the twist department.
I suspect they do that because that is the standard twist for the 44 Magnum and such barrels are cheaper and easier to acquire.