Here's a link to shotgun bore sizes.

http://www.hallowellco.com/bore_size_chart.htm

Nominal bore size for 10 gauge is .775". That tells us that your gun is a 10 gauge. And if your gun measures .771" at the muzzles of both barrels, that tells us there is little, if any choke. I'd immediately suspect that the barrels have been cut. If they have been cut, that will dramatically reduce the value of your gun. What is the length of the barrels?

Voting for anti-gun Democrats is dumber than giving treats to a dog that shits on a Persian Rug