group variation at distance

[6.5Express]

I recently picked up a new (to me) kimber 7 wsm. I shot ladders with 168 vlds and h1000 and retumbo. I have several rifle /load combinations that work well with h1000, and the ladder results here were slightly better here as well, so I chose the middle range of four h1000 increments that clustered the tightest (roughly 0.8 moa with 0.3 gr increments if I recall correctly). I shot a few 200 yard groups with satisfactory (roughly 0.75 moa average with some 0.5 moa 5 shot groups) results.

When I backed up to 4 and 500 yards, groups opened dramatically (2+ moa). Aside from shooter error, what would you guys sugges? back down the charge weight? try the retumbo load? Adjust seating depth?

Any help is appreciated.

 

[Rich Coyle]

Someone on here smarter than me suggested establishing an over all length before you fire a ladder. I hope this helps.