25x45 or 25/223
 

While researching 6x45 I came across this site http://www.dtechsuperstore.com/mili%20Guns.htm
that will be offering (or may already, I haven't contacted him yet) 25x45 AR15 uppers. Does anyone have any experience with this wildcat? I know the 6x45 will push the same bullet weight faster then a .223 but I wonder if the quarter bore will be past the point of diminishing returns. Since either one will be handloaded this might be a nice alternative to the 6x45 for deer. I don't get a chance to varmint hunt so deer and plinking would be my main uses. I still want to be able to use the .223 bolt and magazines or I would look at 6.8 or 7.62x39. .300 Whisper (or 300 Fireball) seems like more of a hassle to make cases for.
TIA
sharps54