What can you tell me about the eight-gauge shotgun in Streets of Laredo?

I recently read Larry McMurtry’s Streets of Laredo, which frequently mentions an eight-gauge shotgun. What can you tell me about that weapon? Jeff Blackstone Dayton, Texas   The eight-gauge shotgun dates back to the blackpowder days. The firearm is obsolete and has not been made in the U.S. since the late 19th century; in fact, gauges bigger than 10 are now illegal. These blackpowder firearms weren’t that potent; a modern 12 gauge can outperform a vintage eight gauge. You can still find eig