I have a RU77 Tang with 17 inch barrel in .30-06. Gets 1.25 or so groups at 100. I have killed with it to 356 long paces on fairly open ground. My hunting partner refers to it as my "long-range rifle".
I'll push it to 400, assuming I have a ranged yardage.(I didn't on the the 356 - that was an eyeball estimate @ 300 - the bullet clipped the sternum and opened up the heart - lucky shot - I now have a Leupold 800i rangefinder).
You don't need a small caliber for such range, necessarily. But I'll push my .MOA .260 to 400 on animals up to 250 pounds or so. I'll only push myself on anything to 500 with my '98 with heavy bbl (.30-06) t, tho it gets inch groups at 300 if I can hold it steady enough. It is a 1,000 yard gun probably, but I'm only good to 500...
I DO know the trajectories for the bullets I shoot in the calibers I shoot. That is far more important than caliber ... And knowing the range via rangefinder is even more so. But so is bullet/energy for the game targeted.
Uh - no - edit. Of equal importance...
Of all that said- for your uses, I would personally go no lower than .6.5 mm with 140 gr min. bullets if you are whacking things to 400 yards, and want clean kills.
If you don't care about clean kills on hogs, even as they are a pestilence, ......well....get away from my coffepot.
