1. "In town" likely means you aren't a resident of Texas. That means you could only acquire a rifle or shotgun while visiting, and only if the purchase is legal in your state of residence. You could purchase the handgun, but the seller would be required to ship to a licensee in your state who would transfer to you.
2. Most importantly, Google "straw purchase" and "US vs Abramski". In short, even if you are a resident of Texas, you cannot acquire a firearm from a licensed dealer on behalf of another person.
There are dozens of excellent gun shops in DFW:
Jackson Armory
Rays
several Bass Pro/Cabelas in the burbs
several gun store/ranges all over the place
But its a WAG if any will have the specific guns you are looking for. You'll waste a lot of gas and spend hours driving.
DFW is a big place. Where will you be staying?