I having a custom rifle biult for the same game you mentioned. I wanted the 300 ultra but when I looked into it I seen it was kinda a joke. what I found was a .30-338. it uses a .30 bullet and a .338 case. it was developed as a 1,000 yrd target gun. very acurate and lots of hitting power. very much like the 300 ultra but with out the big waste of powder and MUCH more acurate. I shot a buddies and had a 1/2" group @ 300 yrds. very nice gun and with the muzzle brake it kicks like a .243

I can give the the # to the guy biulding mine and you could talk with him. oh ya you biuld it on a .300 win mag action

dc laugh