Well, I've filled Varget till the shell wouldn't hold a primer anymore after about 2 fireings, and the shells were hard to resize on the second time around, and after fired you couldn't read the head stamp on the bottem of the case, in my Rem 700 22" sporter and never seen more then 3900 fps.
Here is a victim of trying to reach 4000 fps. right here. [img:center]http://

[/img]
I had an engineer at work the other day tell me about hitting 4100 fps with a 58 g. Vmax on 42 grains of Varget.
When I called him out on it, He stated "well thats what the book says." His rifle Choro'd on the Chrony at 3780...
Just cause it printed doesn't mean it goes that fast in your 243. The Hornady book is a classic example of that!
Show me someone that has proof of reaching 4600 fps. with a 223 wssm.