FWIW, I believe Buffalo Bore is using this bullet in their .38 SWC-HP load, Rimrock says: "g/ch .38/.357 SWC-HP (BHN 5) this is a custom bullet made for Buffalo Bore Ammo Co."
https://rimrockbullets.com/xcart/g-c...-ammo-box.html
I'm not sure how a brinnell hardness of 5 compares to a swaged bullet from Win/Rem/Fed... but 5 is fairly soft. Buffalo Bore is also pushing them damn hard, for a .38 +P load, IMHO. The hollow point is pretty large on those, which probably helps expansion.
I've been very tempted to buy some of those bullets to use in my own loads, but they raised the price of them a lot in the last couple years, and I just can't justify the price they ask, which is in line with jacketed HP bullets now.
I believe Underwood is using a powdercoat cast SWC-HP... no idea where they are getting those though. Or how hard they are.