My BIL is the manager of the sporting goods department for Walmart in some one road town in southern Alabama. He says that he has trouble keeping the Marlin 917V rifle in stock. He says all the locals swear by the tiny .17 HMR. I believe that they're mostly running them with dogs at night. That tiny 17 grain pill makes it through the ear, then explodes like a small grenade in the pig's head. Mario's been posting pics of head shot pigs for years that he's killed with his hornet.
Since you don't have much light make sure that you use a good scope. Just look at Marios(zrexpilot), he uses a good quality Mueller scope. Also make sure that you practice at 30 yards. There's not much room for error and most people will sight in a 300 magnum like yours to be high at 100 yards. At 30 yards it'll be close enough for a chest shot, but you need to know exactly where the bullet's going if you try a head shot.