358156 hp
At large, whereabouts unknown.
Ream it 30 Herret . Takes care of the case taper of the 39 .
Or 30 HRT, the rimless 30 Herrett based off either shortened 30 Remington, or 6.8 SPC cases sized in 30 Herrett dies. You'll need a 6.8 sized bolt face though. The 30 HRT does require its own chamber reamer to reduce the overly generous Herrett spec throating though.
http://teppojutsu.com/30-HRT.htm