Hogs have this almost mythical reputation for being more difficult to stop than a brown bear and it's completely inaccurate. For background on me, this is what I do -
Home - Texas Hog Traps. I sell to the USDA, USFWS, US Park Service, state and local agencies and to land owners and hunters so I have a pretty broad knowledge base to compare against.
I have killed a LOT of pigs with a .22LR, one shot in the head and they're done. In fact, I've killed more pigs with a .22LR than anything else. The vitals are fairly well protected by the shoulder plate on a broadside shot in LARGE hogs (175 pounds or larger). A 300 pound hog is pretty rare in the wild, most people overestimate the weight of a wild pig by 100% so if someone tells you they saw a 300 pound hog, they probably saw a 150 pound hog and if they tell you they saw a 1,000 pound wild pig, they're probably full of bovine waste.
I have never, ever in all my experiences with wild hogs had one charge me when it had another option. The only time I've had them make a run at me was when they were in a trap with no way to escape but even that is the exception. In most cases, even in a trap, they're going to try to get away, not run at you. Placed in a fight or flight situation, the flight instinct is VERY strong with wild pigs. Just standing your ground is pretty effective in making the flee in most cases. A 9mm would do the job just fine aiming for the head and if it's charging at you, that's going to be the best option anyway.
If they've found an area on your place that they feel comfortable in, mowing it may just start them rooting. You're best bet is to either call one of the helicopter outfits and give them permission to fly hunters over your land (if you have a large enough place), set some corral traps where they're active or hire a contract trapper to do it for you. Helicopters will get a large percentage of them if they have a good shooter, I think corral traps are more effective at complete eradication though. You don't want to just run them off, all you're doing is making them your neighbor's problem and they will continue to reproduce and return. Once they start tearing stuff up, it's going to be tough to repair it. They'll root a field up so bad that it's difficult to drive a tractor through it and it's not uncommon for a sounder to tear up as much as 40 acres or more in a single night. You can't just disc it smooth once it's rooted up, getting it back to where it was takes a lot of time and fuel.
I sold a cellular trap door to a farmer in Castroville last year that has the helicopters come over his place, I can find out who it is if you'd like. I don't think he's very far from where you are. If I was closer, I'd offer to come setup a cellular trap for you but, you're about a 4.5 to 5 hour round trip.
Hey if a 9mm is what you have (and he did have proper ammo for this application) then 9mm is what you have.
