The S30 in Rev's photo is definitely the indication of a Steel barrel, 30" when it left the factory and like Doug says. a Damascus barrel will have a D, plus the length. I have owned at least one of all the marks ,S-Steel, T-Twist, K-Krupp, and D-Damascus.. I have had several high grade Meridens and the show some very high quality engraving, super wood and workmanship equal to any American SxS and for reasons unknown to the Hunter Brothersn no cracks behind the lockplates... MDC
MDC-
Good to know the Meriden is not prone to cracks...I was worried that putting this 100 year old shotgun back into service would send me looking for a good stock repair man! If someone knows where the barrel makers marks were most likely placed on these guns from the guns that have them, I'll take a closer look at mine, but all I can find are serial numbers, the barrel length and the single letter T designation for the twist barrels. There is the number 81 on the water table (I have no idea what that signifies).
Doug
Here is a photo of the barrel flats, water table and fore end iron:
