I second the 45-70, got one, fun to shoot, fast to reload, packs a damn big whollop.
I've shot Hornady LEVERevolution 325 Grain through my Marlin 1895 and love it. Keep trying to get out and pig hunt with it. Short barrel, light enough gun, shoots a decent distance (like a rainbow but oh well...) and packs a damn big whollop.
Nothing like detonating a series of water jugs then burying a round in the hillside.
There's also a company that makes a realllllllly nice take-down version and stocks a high penetration round for Alaskan Bear.
http://www.wildwestguns.com/copilot.html
I'd love to get mine done but it's not cheap.
45-70 is easy to get compared to some of the safari double gun ammo.
It's easy-ish to reload, not necked down.
And for my money I love a lever gun. The short gun, left or right handed use and rapid follow up are perfect for a woods gun, pig, bear or dangerous game gun. And it's plenty big enough, like shooting a lead chapstick. Not subtle.
Here's ballistic
45-70 GOVT 325 gr FTX LEVERevolution
Velocity (fps) / Energy (ft-lbs)
Muzzle 100 yd 200 yd 300 yd 400 yd
2050/3032 1729/2158 1450/1516 1225/1083
Trajectory (inches)
Muzzle 100 yd 200 yd 300 yd 400 yd
-1.5 3.0 -4.1 -27.8
So obviously not shooting to 300 yards! But 3000 ft-lbs of energy at 100 yards!
If you want to go cheap, just get a shotgun. Load one mid size shot for small critters, then slugs.