Thank you, Lancaster. Yes, I'm guessing that it might have been a single shot, because the Brits also used Farquharsons in calibers as big as 600 NE at that time. I haven't been able to find any more information. I was wondering if they'd designed a rimless round for the P 13 because they were experimenting with several dimensions of their 276 high velocity round, which they eventually dropped in favor of the 303. My guess is that if they did have a rimless or belted round, someone might have revived it by now . . .

Good hunting!