I fired the double rifle that I am building today. This has sure turned into a project. It is a 577x3" bp gun. Case holds 160grs of ffg and a 600gr cast bullet. Went off without a hitch. first rounds close to regulation. Proof tested it with the same 160gr charge and a 750gr bullet. I will be trying a duplex load next. Only got 1369 fps with straight bp was hoping for closer to 1600fps. I may be dreaming.