Grade 1 = "decarbonized" steel barrels (not Damascus). Any experts on these? I am mainly planning to shoot brass shotshells loaded with Alliant Black MZ at 2 1/2 to 3 drams and an ounce to 1 1/4 shot. But I'm wondering if the B&P low pressure shells I use in my old Ithaca Flues are OK. My Ithaca is 1921. This one is circa 1900.

Send the barrrels out to a sound gunsmith to be inspected. They will either give you a yay or nay on wall thickness safety and can recommend loads and pressure to stay within.

I had two Remington guns with decarbonized steel barrels, both hammer guns. At the time , pre-internet, the word around gun shows was to never ever fire a gun with these barrels. The barrels supposedly crystalized over time and would shatter like an icicle if fired. I would bet it was just a tale but I sold the guns long ago because of that rumor.
terc

As an old Pittsburgh metallurgist, I can put that old tale to rest. Most people don't know this, but all steel is composed of crystals. "Decarbonized" was a term used to distinguish the newer methods of iron and steel making from the wrought iron days. Given the age of the gun, it's likely the steel came from a Bessemer converter that blew air through the molten pig iron to remove the excess carbon. So, simple carbon steel, weaker than modern alloy, but steel nonetheless.

I was hoping to hear more about Remington shotguns of this era