constructive pointers needed please

[chaneylake]

this is my 300 yard target shot today, 11.7 inch bulls-eye

10 shots out of a cold barrel with no pryor shots, wiping between shots

.40-65 Shiloh, Jones 422 grain bullet, Swiss 1.5, 55 grains, basically no compression

can anyone of you see what I need to do to tighten up groups of this size, I am staying pretty consistant with groups such as this one posted

what would be an approximate sight setting for 500 yards, my 300 yard setting is .55

target should be rotated 90 degrees counterclockwise but my software is no accepting adjustments