I was just thinking of having one made up
35x378 JC its just a 378 shortend by about 1/2 inch and necked down to 35.
Jim cothbert did this in about 1973 i had mine made it was SER# 640003 on a mark 5 28 inch airgau/barrle canjar trigger
i sold it to a buddy of mine and he sold it to some gun store last i saw it it was in the gun shop some fool had blown the action on it ...
What i am looking for is a gunsmith who might still have reamers a gaud/ for it anyone out know?

Pottsy

Sounds liek a screamer. Reminds me of Real Guns' 358-378. Chambered in a Ruger #1, it was basically off the charts on both ends of the cartridge.

Yes the 35x378 JC was a real kicker .
jims cuthberts idea was to just shove IMR 4831 into the case till it was full and cram a 250 grain slug on top crazie bas#$^#@ there was no reloading data for it so i started off running
85 grains H4831 with speers 250 grainer in it and went
up from there till i started blowing primers in a few of the cases. the primers would just fall out after thay were ejected from the gun that was after i had started loading it up hot i dont want to start posting the load becouse i dont want to get into trouble here ..lets just say that
i git the 250 grain slug to come out off the gun at an speed unmatched by the 378 full lea/ or most any other wild cat on the same case ...i remmber most the flame that came out it was about 17 feet long and very yellow with a blue hue it looked like a laser beem ..i can tell you that it shot the slug out as fast as the full lea/vertion then again remmber this gun finlly gave up the ghost and blew
the action .no biggy though at the same time we were shooting old phonograph needles out of another gun it was necked down from 300 WM ahhh thoses were the days money to burn ..and no wife to give me hell

pottsy