I have no first hand experience, so please let my opinion be the last thing you consider, I have only killed a small Bull elk with a .270 Weatherby Mag, using a 150 Grn Speer Grand Slam ( 1980 ) . However just recently , on "Steve's Outdoor Adventures" Steve, himself , shot a Bull Elk at 220 yards with a 6.5 Creedmoor. I was shocked !!! I could not even believe he would hunt elk with that cartridge , but he shot the elk and killed it . So I guess if a round as " Mild " as that round can take elk at modest ranges, your other 6.5's should be able to handle the job very well, with the correct bullet. Or let the kids use the 270 Win. with a 150 Grn partition. IMHO