I am new to this site. And to long range shooting. I shoot 300 wby. Recelently fitted a bushnell 6500 elite scope using burris rings and shims. I have used a chronograph to verify the velosity. My problem the bullet drop is fewer clicks at 400 and 880 yds than my bullet drop calculator states the number of clicks. Should be. Either my moa of 1/4" is in accurate or the shims have effected the moa which does not make since. Any suggustions? JQH