LukeinNZ
This 600JDJ is on a Ruger #1 that was built by SSK a few years back for me. It is a 577 nitro case blown out to .620 caliber. I am having AHR (American Hunting Rifle) now build me a 600 OK on a CZ action. Power-wise & case capacity is pretty close. The JDJ is a rimmed case and the OK is a belted case for a bolt action. Any of these 550's, 577's, or 600 will be killers in the extreme. The impact of these 620 caliber bullets on soft targets is something else