i have a new Pedersoli Hi wall in 38-55 1:12 twist that i took for the first shots today to the range.Im shooting a Accurate money style 350 grain bullet sized to .381 it appears the bullet is tumbling and keyholing at 50 yards using 22 grains of 5744 at about 1250 fps which is the starting load in the Lyman cast book.Some bullets are not even hitting the 28x48 target frame.i slugged the barrel and it looks like its .378-379 would this oversized bullet cause this?