A lot of feral pigs in Southern Australia can be quite small. A lot of guys used to use 22 Mags (inadequate) but also .222's, .22/250s etc. A .243 is good too.

Some of the Southern pigs can get quite large however.

Northern Australia, to my experience often has a greater proportion and incidence of large pigs.

So a 7.62x39 is quite OK for many of our feral pigs. And with proper bullets and placement, also will handle the larger ones too.