My 243 mag.! But there is a ammo issue.!! This is basically a necked down 25-06, but gets slightly more velocity than the 6mm weatherby mag.. Gotta say though, I was inspired to chamber this rifle after I sold my 25-06 & was really missing its performance.. I chambered this rnd on a pre-exsisting 243 mauser by simply cutting a 243 reamer down (head dimensions) so it would not cutt any larger than .470 in diameater, then I simply ran the reamer deeper (used a drill press) & used a full length sized & necked down 25-06 case to set the head space, so its really tight.. FWIW, I already had the reamer, rifle & brass.! so this really costed me only my time, which is much cheaper than a new 25-06.! With that said & without going to this extreme, my vote would go to the 25-06 or 6mm Remington..