I have a .260 AI, essentially the same performance. Sending a 140 VLD at 3070 fps, I have killed many, many critters, including several elk, specifically a 6x5 bull at 715 yards. I'll post a video of my experiences with this cartridge, and a couple with a 180 in a 7mm rem mag are mixed in the video, but it tells which ones in the description.
However.....If I was going to get a firearms specifically for elk, for myself, I would want 7mm rem mag performance or better. Not saying that a 6.5 is not enough, I love mine for an all around gun, and my nieces that hunt with me love it, my 12 year old niece killed her first big game animal with my .260 AI this year, a late season cow elk at 610 yards, with a single shot directly through the heart. Talk about a proud uncle moment!!!
I don't wish I went bigger when I built this rifle, it does exactly what I wanted it to do, great performance, I am confident hunting anything in north america besides brown bear with it, it has very low recoil, making it easy for new shooters to shoot exceptionally well with it, and it is cheap to load for and shoot. I am however, putting together a .338 Norma mag....not because I need it by any means, but because it is just going to be an awesome rifle!!!