A GOOD iron barrel is superior to the steel used in most American ML barrels. Its not brittle but instead tough. Modern 1010 alloy steel hot rolled with no added lead or other additives will work fine even for low pressure smokeless if its of the proper quality. 1010-1018 was and might still be used for some 45 ACP barrels for example. 1010 is steel in the modern world, 1009 would be "iron" but it would not have all the slag inclusions most people associate with wrought iron.
Dan
Have you ever seen a source of commercially available 1010? I spent a week one time, even calling mills in PA, and could not find 1010 in any form in the US larger than wire for making some kinds of galvanized wire rope. I was told that mills in India could provide it but never found a situation where I could communicate with someone and make myself understood. This was 5-10 years ago.
I would give a pretty penny for 1 1/2" rods of 1010 and also flat bar stock for machine made and forged iron barrels. It would probably weld similar to wrought iron without the silica. It basically is pure iron...
If you know how to find 1010 in workable sizes for commercial sale I'd love to hear about it.