I don't have anything I'd shoot pat 1,200 with any confidence even on a big rock but I'm pretty well in your same boat on game. I've taken a few critters considerably farther but life starts to get real complicated beyond 600yds so conditions really have to be right to stretch beyond that.I shoot several rifles from 500 to 1200+ on a regular basis. Another rigs gets to go out to a mile once in awhile.
All of this is to be confident in taking big game out to 600 yards.
I could not have said that better. When I was younger pretty much everything I shot was under 100 yards. Then one day in a field I shot a buck at 242 yards and it felt like I shot it across the ocean. In fact, it was laying in an open field and my brother after hearing my shot said he was coming to help. When he got to me he asked where it was. I replied in he field. Him: where? Me: over there. Him: where? So I pointed it out and he replied "you shot that SOB way the F over there???" To my brother 100 yards is still a long ways, but now for me anything less than 300 is cake. Last year I killed a buck at 200 and I think I actually hit the very hair I was aiming at. Now 500 is tougher with wind but I'm very confident in one shot kills here, but for me right now LR Hunting is past 700. In a few years I'm sure it will be farther than that for me.
So in conclusion I think Long Range IS defined by out personal capabilities. If he's proud of that shot, let him be. I bragged for years about dropping a buck at 242 and got lots of oohs and aahhs.
Ps it is actually VERY hard to find a shot past 200 here. You have to purposely position yourself in a spot to shoot farther and that usually in a VERY tight window.