cartridges in leverguns
I'd like to see Winchester chamber their 16" barrel Trapper/Ranger in 10mm Auto. They hold 9 rds in .357 & 44 Mag, so you'd get 10 easy with the 10mm.
With a 20" barrel, something like their Model 94 "Trails End" holds 11 rds of 44 mag, so you could probably pack in a Baker's Dozen in 10mm.
I'd be excited to see Winchester or Marlin exploit the ballistics of the 10mm out of a carbine/short rifle length tube.
Don't know if you could shoot 40 S&W out of it too, but then, except possibly for cost, why would you want to?