I am new to reloading and can only relate information which has been given to me by my more experienced reloading friends. I'm sure the following is unusual, but I thought it was very interesting. A reloading friend was talking to another shooter who was very dissatisfied with a brand name rifle he had purchased. Apparently his accuracy was all over the place and he was about ready to give up on the rifle. My friend offered to take the rifle and work up a load for it since he shot high power and understood most of the factors involved in loading for rifle accuracy.
My friend tried to work up a load, but ran into the same problems as the rifle's owner. One factor to consider, as you are probably aware of, is jam/jump of the bullet. My friend was trying to load the round so that the bullet was up in the chamber and had minimal jump. From his experience, this provided the best stabilization for the bullet. When he had tried everything he could think of, he called the rifle manufacturer (or maybe it was the bullet manufacturer...possibly both) and found that he needed to let the bullet jump a little to the chamber. Voila! He had a very accurate round for that particular rifle.
He gave the rifle back to the owner along with the reloading recipe, and they lived happily ever after.
Fly