I've narrowed it down to 6.5 Grendel, 6.8 SPC, and .458 Beowulf, with 6.8 SPC in the lead. I've read that the first 5-7 rounds of 6.8 will feed from a standard USGI 30-round magazine, I am assuming it would feed from a 5-rounder. Anybody know if this is true? I also like the wider variety of .270 caliber hunting bullets I can load for the 6.8. Also uppers and 6.8 parts generally seem to be less expensive.
Are there any pro's or con's I should know about these choices I listed for hunting? Or are there any other calibers I am forgetting that would suit my purposes?
Well first the .458 is Socom not Beowulf. The Wulf is .50 and not a good choice for ranges out to 250 yards. The farthest shot I have made on a whitetail with my Beowulf has been 140 yards with the 300 grain FTX bullet. I wouldn't feel too comfortable pushing a shot too much farther than that.
The Grendel is what I chose for my medium caliber AR. I am running 129 grain SST bullets and a 19.5" barrel with good success. So far my longest shot with the Grendel was last Saturday when I took a coyote at 225 yards. I think the Grendel would do well for what you want.