7x54 was quite popular wild cat caliber in Finland after WWII. You mostly could see it in rebored (original caliber 6,5 Japanese)and civilized Arisaka military rifles. Ordinary twist of barrel is quite low, just good for light 5,1g bullets which are same whose SAKO made for their own caliber 7x33. There is too 7x53R which has necked down 7,62x53R case.