We all get terribly revved about "which cartridge is best" but it's got bugger all to do with the cartridge, it's all about the bullet and what speed you want to drive it at for the intended quarry, range and conditions and how accurate you and your gun are.
First job is to make sure you can put it where you want to. A good shot with an accurate rifle will happily put a Red Stag down with a .243, and if it were legal I'm sure some would do it with a 22-250. We go bigger to give ourselves a bit more margin for error and to achieve a quicker more humane kill.
If I'm after fox under the lamp I want something that is +/- 1" or less to somewhere between 250 and 300 yds and will disintegrate on impact. I achieve that with a 70 BK @3600 fps in 6mm, others will choose a 50 grain at 3800 in .22CF. Both will do that job well.
If I'm woodland stalking for deer I want controlled expansion in a 120 to 150 grain bullet at a 2600 to 2900 fps to avoid too much carcass damage. I'm not worried about wind inside 200 yds. Could be a 6.5mm, could be a 30 cal.
On the hill on a windy day or if likely to be taking longer shots I prefer to take something that shoots a high BC bullet, again could be 140 grain 6.5, 160 grain 7mm or 200 grain 30 cal. My preference is the 7mm because it carries it's energy well and doesn't recoil as much as the 30 cals, but others might not be worried about the recoil.
For Boar I want to shoot something in the 160 to 200 range, BC irrelevant, speed can be relatively slow, but it needs to make a big hole. 7mm, 30 cal, even 30/30 is going to achieve this.
You may choose to argue about some of the above numbers, you may well do it differently to me, but you have to agree that accuracy comes first, bullet size, construction and the speed you launch it at comes second. When you have made a decision on what you want to achieve on those fronts the "which cartridge" question can start, and there will be more than one answer to both the calibre and cartridge question.
Is the .308 perfect for all of the above. Yes you can load 180/200 grain for Boar at 2500 fps which is more than enough. Yes you can load 150 grain at 2800 fps for woodland stalking and it will do as good a job as most other options, better than many. Would it be my first choice for a windy day on the hill or longer range shots - no it wouldn't, but plenty of people do well enough with them in 600 yd matches to prove that they can be used effectively for that job if you are good enough with your trajectories and wind reading. Would I use a .308 on a fox, 110 grain at 3200 fps, again not ideal but it will do the job in most instances, you would just be a bit handicapped in the wind or over 200 yds under the lamp when you're not quite sure of the distance and have to be quick.
You could well argue that with it's extra power a 30-06 would get over the issues of speed for the hill and the foxes and loaded down a bit would do the other two jobs just as well. You could say the same of many of the 7mm calibres which have the additional benefit of higher BC bullets when you need them and a bit less recoil.
My "perfect" calibre....I don't have one, just pick up the right tool for the job in hand.
It goes on and on.
And why would you only want one gun anyway?
very funny ! I know I usually don't let that kind of chopper rile me but our colonial friend '10' ringpiece got on my tits with his attitude after only 9 posts !
