Michbob,
Went home last night and looked around for info on the cattle killer, couldn't find a direct reference to the round but WW Greener's The Rifle, pg 520-521 talks about the device(gun?) it self. There was ref to a 310 Greener which appears to be similar to the 310 Cadet but with a shorter case, again no load or dimensional data, sorry. If someone is making brass for this puppy what in the devil are you supposed to use it in? I've never seen reference to anything other than this slaughterhouse device chambered for it. In my slightly warped mind I see someone in head to toe camo stalking thru the woods with his cattle killer and a hammer blowing on a grunt call. Time for another beer.
Best.