I think it is the extractor groove on the cartridge cases that cause the problem. Many cases would work but the extractor groove is just around that .411 size so that there wouldn't be much if any brass left to thread it with.

I think that one of the .300 to .350 size magnum cartridges would be about as small as one could go. The 8mm Remington Magnum looks good with a groove of about .475". The .300 Winchester magnum and .300 Weatherby are some other choices.
The .350 Remington Magnum is another one with a extractor groove of .475" too.

Another thought are some rimmed cartridges such as the 7.62x54R Moisin Nagent cartridges with a .486" base dimension. The neck narrows down to about .30 caliber so it has a smaller opening for the exhaust.

A brass shotgun shell might work too. One could machine a plug for the one end to narrow the exhaust outlet down some.