Common, yes, but TX is off the charts for open carry. When I lived in Houston I would often see people coming out of the church in my area with a rifle on their back. I saw a guy at a McDonalds with an M-16 on a shoulder strap, Baretta 9mm on his hip, and something small in an ankle holster. He unsurprisingly got into a big, chromed pickup with two shotguns in a rack in the back.