Nope, no rules whatsoever. The Texas penal code does not stipulate what gun, how many guns, how those guns are modified, or anything along those lines. If you wanted, you could carry an AR pistol, 5 handguns, 1 handgun and 10 extra mags, a handgun with a weapon light and a slide mounted red dot sight, a PTR PDW pistol 8" .308.....the sky is kind of the limit in that regard.