The thing I found with my Ultra, is as most here find, the long throat......so I tried loading mine longer with the lowest powder listing in the book (hornady) to allow for pressure possibilities. I finally ended with a load that will shoot all three 87gr Hornady bullets into a 2 inch target at 100 yds.
I'm using 39.8 grs of H4350, Winchester primers with any of the 87gr bullets (vmax,hp,sp) and seating to a col of 2.75. The first vmaxes I fired I had 3 touching, I was a happy shooter to say the least, so I tried seating them all that way and it seems to work in my barrel.
I had another poster on the board tell me give up on the 87 grainers, but I had to stick with it and it worked out. I don't shoot the 243 that much but now I have the confidence with what ever 87gr bullet I choose.
Loading lighter powder weights and giving up velocity beats having a shotgun pattern and the agravation of a poor grouping rifle. At least for me.