All I know that it is a .577 Nitro blown out to take the .600 nitro (.620 bullet.)
Can anyone shed more light on this.

Check Cartridges of the World.

George

Isn't this basically a rimmed version of Robgunbuilder's 600 OK 3"? If it is, you should be able to get 2400 fps with a 900 grain bullet. Not that I would want to!!!

ASS_CLOWN

it is a neet caliber what you looking to chamber it in i have shot it in a few ruger 1's and a farquson action.

the adv velosity in the ruger 1 is about 1700-1800fps but you can get it to 1950 of course the load data i have only uses like 3 differnt types of powder and there is load data for more than that.

id say your better off chambering to 500 jeffery or 500 a-square cause the ruger 1 really dosnt leave much beef on the chamber walls when opened up to such a huge caliber such as the 577 or 600.