Re: How do u test for an accurate load?
I like to clean between powders during load work.
As far as waiting between shot. The group needs to be fired in the same wind conditions, from first shot to the last. Before I started shoot benchrest, and see guys shooting over wind flags. I don't know how a slight breese could open up a group at 100 yds. I know for sure in the past, that I have fired groups, thinking that they were not that good, the wind just opened the group enough to make it bad. you need to see a field if wind flags set up on a range, to see how much the wind blows.
For 600 and 1000yds benchrest, we fire sighter to zero and to dope the wind, and then try to fire all record round under the same condition. If it changes you are screwed, because you can't fire sighter, after you go to your record rounds.
Over long range the wind comes in all directions and speed, very hard to learn.
Just a few strips of survey ribbon work great.