Howdy Again
Thanks for all the great information. I will get back to that gentleman on the other board and set him straight.
I looked up my two old Stevenses, and one is a Model 355, the other is a Model 250. The 250 has the incredibly low Serial Number of 305. At first I thought it was an assembly number, but a member of this board assured me that it is the SN. Yes, Homeless Joe, they are Cowboy guns, but rest assured I will not be cutting barrels or altering them in any way. I only shoot Black Powder in them to keep the pressures down. The hammer gun is my current Main Match Cowboy shotgun. It always gets plenty of compliments from those who know shotguns. I am nowhere near as fast with it as some of the guys who have newer guns, they can sweep both hammers back with one sweep of the hand. I cannot do that with these hammers, but I couldn't care less, it is so much fun to shoot this little beauty. I call it little because unfortunately some MORON cut the barrels down to 24". I dearly wish they were the original length. The 355 is in tougher shape, the checkering has been worn mostly smooth and varnished over many times. The 250 has had the bores polished and the forcing cones cut for modern shells. The checkering has been freshened up too. So the gun is clearly not in virgin condition, but the work has all been tastefully done, it was done before I bought it, and I love shooting it. There is still plenty of color left in the case hardening too.
Here is a photo: 
 
 There is no marking at all 0n the barrels of either of these guns regarding gauge, or the type of steel used in the barrels. They are plainly not Damascus, but there is no marking at all. Here is a photo of what I believe is the Serial Number of the Model 355, but I suppose it could be an assembly number. The patent date on the 355 is March 19,1907. There is no patent date on the 250. 
 
 I think I will be ordering that book from Amazon,
Thanks for all the help.