Antique or curio guns manufactured before 1899 and replicas thereof which do not use rim fire or center fire ammunition are not included in the definition of "firearm" as it is used in Texas Penal Code Title 10, Chapter 46, which governs weapons.
From Texas Parks & Wildlife;
Firearms
Game animals and game birds may be hunted with any legal firearm, EXCEPT:
Ӣwhite-tailed deer, mule deer, desert bighorn sheep, and pronghorn antelope may NOT be hunted with rimfire ammunition of any caliber.
Ӣshotguns are the only legal firearm that may be used to hunt Eastern turkey during the spring Eastern turkey season (see County Listing). Rifles and handguns may not be used to hunt Eastern turkey.
Ӣpellet guns and other air guns are NOT LEGAL.
Ӣfully automatic firearms are NOT LEGAL.
Ӣfirearms equipped with silencers or sound-suppressing devices are NOT LEGAL.
Ӣa shotgun is the only legal firearm for hunting migratory game birds (see Definitions - Legal Shotgun).
Nongame Animals (Non-Protected): Any lawful firearm, pellet gun, or other air gun is legal.
Muzzleloader: Any firearm that is loaded only through the muzzle. Note: A cap and ball firearm in which the powder and ball are loaded into a cylinder is not a muzzleloader. Muzzleloader deer seasons are restricted to muzzleloading firearms only.
Possession of firearms by felons: A convicted felon,
regardless of where the conviction occurred, may not possess or use a firearm (as defined by Penal Code, §46.01) to hunt in this state. Under Penal Code, §46.01,
a muzzleloading firearm is lawful if it is an antique or curio firearm manufactured before 1899
or a replica of an antique or curio firearm manufactured before 1899 that does not use rimfire or centerfire ammunition.
Having posted all that you must keep in mind that I am not an attorney and this should in no way be considered legal advice. [/b]