You did OK (4" Groups @ 100 possible)if you bought fast powder like 777 to push that monster bullet. Use 80+ grains to start & bring the Ben-Gay to alleviate shoulder pain...lol.You may have to take that 777 powder charge to 90 in that 54' Then you may have to deal with somelead-shedding in the bore too.

Otherwise, listen to Cayugad. The man knows conicals pretty-darn good with normal powders like Pyrodex, APP & Goex. Dave's even helped me with 777 loads when I was experimenting with 13 different conicals in my 50-calOmega last year.