TexasCHLforum.com

Counties can regulate properties less than 10 acres. State preempts regulating anything larger.

So, no, you cannot discharge a firearm in Caldwell County on property less than 10 acres, just like being inside a city limit.

This issue is where people get confused about the 10 acre rule. If the county has chosen not to regulate firearms discharge, you can shoot on any size property in unincorporated areas, as long as you keep the bullets on your property. But, if you are buying property to shoot, best to buy more than 10 acres to be safe.

ETA: I don't think shooting a feral hog would classify as self-defense, just MHO.