I used the Hornady 129sp in a .260 ( around 2900+) on an axis buck and a mouflon ram. My impressions is that, at that speed ( under 150yds) it was still a slower opening/penetrating bullet. I had the rifle reamed to the them "still a wildcat" 6.5/284, used the Nosler 125/120 (3200fps each) and it was a lightning bolt killer! Of course, I never killed anything over 320yds or so. I zeroed it 1" high at 100yds, and it was great for
threading the needle" brush opening shots. It did not feed worth a flip in that Mod 700 SA. I traded it off. So, in my short experience with the 6.5 ( 260 & 6.5/284) I would pick the 120BT. I'd use that 125 partition on elk. I also would build a 6.5 Sherman if I ever built another wildcat. Yep, with the 120NBT.