You can easily make 2400 fps with 125's out of the .300 with a 16" barrel, and they kill deer & hogs well at reasonable range. Same magazines and bolts as the 5.56 in an AR. Lots of subsonic options if you desire.
You need a different bolt for the 6.5 or the 6.8, and possibly different magazines, so slightly more hassle to feed.
I've killed deer with a .223 as well, and it worked fine. Don't expect a blood trail.