Here is some examples of what BP loads can do.
In this case, my 40-65/16 twist HiWall 

Your 38-55 /112 twist should do this kind of accuracy.
#7out the BACO  JIM#371359E bullet.

Last Sept. I shot a similar 99-3X at 500yds to set another record at Lodi BPTR regional
with my Brg BPCR, cal 38-50 RemHep/10 twist with that
Buffalo Arms  JIM#371359E Dual Diameter Elliptical PP bullet
over 63 grains of Swiss 1.5
beltfed/arnie