Seater die

I've noticed on my .45 rounds that I get a buldge on the case that is more pronounced on one side than the other. This is true with both SWC and ball. I am using Lyman dies all around on the dillon 550 with the exception of the expander of course.. Would there be any advantage to using redding's comp seater die? It might be the that it doesn't even matter, but surely a centered bullet is better than one that is offset. I played with the belling on the powder funnel on the dillon, and I cant improve on my situation. I thought it might be the stem so I run about 10 230 fmj's with lapping compound on the bullets chucked up in a drill and tried to make a more custom fit between stem and bullet, but no improvement on alignment, but it did get rid of the ring. Are there die options that are preferred over what I have. 
Thank you.

A bulge all around the bullets base makes the loaded round have an  hour glass type shape. Normal when the siziing die is over working the brass. On one side is from a crooked seating of the bullet. Working on the seating plug shape was a good idea.  As far as sizing dies, Redding is making a new  Duel Ring Sizing Die that may make a difference?  I have not tried one.   http://www.redding-reloading.com/online-catalog/124-dual-ring-carbide-dies

Try loosening then re-tightening the seater die with an empty cartridge case in the shellholder with the ram all the way up. Sounds like the die is not concentric with the cartridge cases as the bullet is seated.

It has been my experience that when this happens it's from the expander die and the case not being seated fully into the shell holder meaning sideways with the total rim in the shell holder but not to the very back of the "U"  ( hope you understand this). The case ends up being cockeyed and not parallel to the expander die or shell holder and expander puts a bulge in the case on one side. Seating the bullet exaggerates the the bulge on the case but it initially happens during expanding.

Check to make sure there is no dirt or debris in the shell holder that's holding up the rim of the case from being fully seated in the shell holder
YMMV


Virgil

Agree with Virgil. The bullet just follows the path the seater has made.

I will add that I think the most important step when loading for accuracy is expanding / belling.