Darrel Martin said:I think you can take any particular reasonable powder charge and tune that charge weight by changing seating depth . I doubt that every charge weight can be made to shoot equally well. I have a friend who selects a powder charge ,then shoot different seating depths to tune it.I have sat and watched his groups shrink or grow as he shoots different lengths until he selects the best load based on length.
I think it is more common to set a length such as .010 to .020 inch off the lands or in the lands and tune with changing the powder charge. Then fine tune with slight changes in seating depth.
To more directly answer your question,I think you will find that different powder charges will require different seating depths to get that charges best accuracy.