It's not always the ammo or the gun that is the problem.
I've posted this before, but here is an example of what happens when form is not followed exactly.
These shots were alternated with the same hand loads, the only thing different was the slight amount of pressure on the butt stock of the rifle, that's it.
The range was 100 yards, and the difference in point of impact is quite noticeable.At 200 yards it would be twice the distance between the two groups.
Cat