Light affects some and not others.
For me it was even to the point on some ranges I could shoot right through a change, noticeably on open ranges like Perry. But on closed ranges like Deadwood, it sure could throw me for a loop.
Finally I got to the point where I could shoot half azz decently and even though it could throw elevations shots they would generally stay barely in the 10 ring if I was good on wind.
Always said that a 10 at 600 is a warning to get your head out of your....
Of course if it was easy everyone would do it.
A coach there once... on a practice day screwed my clean... 17xs deep at 600 he reminded me not to [bleep] up. His exact words. a wobbly 10... and a wild 9 and then whatever else... 199 and probably 17.... there are all kinds of variables. He made me a MUCH better shooter that day though. Much as I hated him at the time.
Again PM or contact me if you are ever headed that way. Who knows, maybe i'll have or make time.
Jeff