It depends on the shell you fire.
20
.410 bore is .410 inches 28 gauge is .550 inches 20 gauge is .615 inches 16 gauge is .662 inches 12 gauge is .729 inches 10 gauge is . 775 inches
Conventional shotguns run from 10 gauge (very big) to a .410 (smallest). The most common are 12 and 20 gauges, a little less common are the 16 gauge and .410 (.410 = 67 gauge). Some of the less common gauges are 32, 28, 24, and 10 gauge. There are also monster 'punt' guns usually 6 or 8 gauge mounted to a boat. The smaller the gauge number, the bigger the gun.
I have purchased a 410 & 20 ga. I ga $65 for the 20 and $90 for the 410. I am looking for a 16 if anyone has one for sale, email Bbill53@aol.com
12, 16, 20, 28 gauge and .410 bore. The 28 gauge is most rare, worth three to five times the value of the 12 gauge
Winchester did not make a shotgun chambered in 25 gauge,as a matter of fact there has never been a 25 gauge shotgun made.Available chamberings were 12 gauge,16 gauge,20 gauge,28 gauge,and 410 gauge.
A SxS in useable but not like-new condition will bring between $100 and $250. A 20 gauge or .410 will be in the mid to upper part of that range and a 12 or 16 gauge in the lower to middle part.
12, 16, 20, 28 gauge, or .410 bore, depending on what it is chambered for.
I don't know how long you want to go back, but Browning has made their Citori model in 410, 28, 20, 16, and 12 gauges for more than thirty years.
A SxS in useable but not like-new condition will bring between $100 and $250. A 20 gauge or .410 will be in the mid to upper part of that range and a 12 or 16 gauge in the lower to middle part.
There is no way to determine the gauge without seeing the gun. Assuming it is one of the standard gauges, you can measure the inside of the barrel. 12 gauge is .729", 16 is .662, 20 is .615, and a 410 is .410.
If I had to guess, I'd say 12 gauge since that would be the most common. But it could be 16, 20, or .410. It is possible, but not likely, that it is 10, 24, or 28 gauge. Anyone familiar with shotguns should be able to tell you just by looking, but you can also measure the diameter of the barrel. The diameter of a 12 gauge barrel should be approximately .729 inches, a 16 gauge .663, a 20 gauge .615, and a 410 is measured as a caliber .410 inches. The diameter at the breech will be a bit higher than these measurements and at the muzzle it will be a bit smaller.