It took us a while to figure it out. You can take out the legs, and at least you have slowed them down. You can take off a jaw and they can't bite. but if you want to immobilize them, and this goes for the bloaters, the screams, and the roamers, you go for the brain stem. That little, well-protected piece where the brain meets the spinal column.
I don't think it was until day three that we figured that out.
Knowing that, changes the type of weapon you want to use. First of all, guns just aren't that effective. Despite what you have seen on TV, there is just not that much force. A shotgun will do a lot of tissue damage, but for you to get to the brainstem, the shotgun needs to be within feet, not yards, and you need to be behind them. SO if you are going for a gun, hope for something large caliber, and hopefully with a hollow point.
Since the motel is in San Diego, and not Wyoming, there was a lack of high powered rifles. This is what we found that works: Crowbars, Axes and baseball bats (go aluminum, about 5 biters in, you don't want to be splintering pine). A sledgehammer is great, and so is a pickaxe, but I'll be honest, it will wear you right out.
It took us a couple of weeks to build "the Clapper" but it was very effective. We strung to heavy security doors that we took from the inside of the motel and hinged them together. We hung a pole out in front of the main entrance (blocked by the cage). We could lure on or two wanderers in and then with a cable system, we would drop the heavy doors, that would "clap" on the walker's heads.
High level reasoning isn't a strong suit, and the clapper was a pretty effective way to clear out one or two lingerers, after we had cleared out the crowd. Clearing the crowd, well that was another story all-together.