Yes, they are. I know of at least two guys (one in Cody, WY and another around Rapid City, SD) who make brass for obsolete cartridges. They charge pretty well for their products, which are at the very least visually quite pleasing. They’re doing as I mentioned - machining them out of 260 bar stock. As you can guess, the cost of the end product causes your breath to escape out of you as tho you were just punched in the gut. Still, as you say, it’s the only option for those old timey rifles and pistols.
re: T-15 vs. O-1/A-2/etc: If I’m cutting something like brass, I don’t need really good HSS like a T-15. O-1 is just so cheap compared to good HSS...
And mind you, I like T-15, or Rex-95. Lately, I’ve been playing with inserted HSS tooling from A. Warner Co. in PA. Neat idea - combine the flexibility of HSS with the speed of insert tooling. Really cool idea. I like their threading tool because it is external on one end, internal on the other.
You sound like you use your machinery more than I use mine. I have a 16x40that I got 26 years ago for one offs and general repair parts. Often months will go by without my using it and other times I’ll be using it in all my spare time for a couple of weeks. BTw that is a picture of a 300 ton press. I got a good deal on some t-15 (about ten years ago) and have been using what I bought then whenever I think the time making the tooling would be worth it - which is not very often. BTW it came with a 3 jaw, a 4 jaw and a faceplate. They could have skipped the 3 jaw - I never use it.