Hi Dan,
The best all-round calibre is quite simply the one that:
a) You feel most comfortable with
b) You are most confident with
c) That satisfies the type of shooting that you are likely to do.
Bear in mind the type of bullet you use will have a great bearing on how successful the effect is on your chosen quarry. On almost all our courses, I get asked what calibre I recommend, and the fact is it really is your own personal choice.
However, I can tell you that the calibre I most favour for everything from Muntjac to Cattle is .30-06. It has plenty of energy, a huge range of bullet weights, a relatively soft recoil (almost a shove rather than a kick), its what I use all the time. However, I would add that as long as your capable of putting the bullet precisely in the right place, then any deer-legal calibre will do the job.
Regards,
Mike.
Mike Allison
Managing Director - Jelen Deer Services
01264 811155