I shoot 777 fffg powder out of my encore shoots great shoot black powder out of my 20ga. double barrel pedersoli 70grs was told by mfg. to decrease load 40 percent by vol. 70gr black = 42gr of 777 fffg went to texas shot a nice rio just wondering if this conversion is correct would like your opinions this is my first post here enjoy muzzleloading looking forward to your input THANKS