Are you talking major load changes such as different bullet or powder? Or have you seen changes with just tweaking the powder charge or seating depth?
I can usually tell in my ladder test target if it is going to cold-bore group well by a slower round, (perceived slower as in the target below,) grouping with or slightly above the node.
I don't tweek the seating depth like many of you do, .3moa is is perfectly fine with me. I only have a 700 yard range so .3moa is wonderful. Although I do have loads that shoot much smaller.
Do your findings get rid of any potenetial clean-cold bore fliers?
Here is my test target for that load above.
Unfortunately, that load is no good since it doesn't jibe with my sight graduations beyond 300 yards.
Sometimes I just get lucky like here.
Here is that load fouled bore.
[ame=http://www.youtube.com/watch?v=RyEwORxRaXo]Howa 1500 in 30-06 at 400 Yards - YouTube[/ame]
The next day, cold-bore.
[ame=http://www.youtube.com/watch?v=275t8chmGRk]Cold-Bore, High Wind, 400 Yards, 2 - YouTube[/ame]
That is about 1/2 an inch difference at 400 yards; and that is just getting lucky with the load. If the cold bore deviation showed-up, I'd have continued with the ladder test until I found another node. I could have gone a lot heavier with the charge weight.