K80 question about his drilling give my an idea about the old swiss cartridge 10,3x60R. this is the metric designation for the old british 450/400 2 3/8 BPE with a max.pressure of 15,53 tons per sq.inch. The 450/400 NE 3" have a max. pressure of 16 tons and the 3 1/4 NE have 16,5 tons and thats near.unfortunately have the swiss round a max. bullet dia. of .413 but all other cartridge measurement are under this of the big sticks. there are a lot of combination guns for the swiss cartridge around in switzerland and and its possible to rechamber it.