Modern handguns SHOULD be able to handle steel cased ammo without issues. Lower pressure rounds mean that a softer barrel can be used, but ALL steels used in gun manufacturing have to be hardened to a degree. Even the softest barrel should be harder than the steel used in the cases, not considering the fact that the cases themselves are coated with a polymer that should minimize, if not eliminate any possibility of damage to the barrel/ramps. Not saying that it couldn’t or doesn’t happen, but if the manufacturer made the steel soft, then you’d be seeing other issues as well, such as damage to the lugs, pivot cams, etc.
From the Ruger SR-1911TM manual:
“The SR1911TM pistols are compatible with all factory ammunition of the correct caliber loaded to U.S. Industry Standards, including high-velocity and hollow-point loads, loaded in brass, aluminum, or steel cartridge cases. No .45
Auto ammunition manufactured in accordance with NATO, U.S., SAAMI, or CIP standards is known to be beyond the design limits or known not to function in these pistols.”
I’ve heard that Glock and Taurus both say that steel cased ammo is perfectly acceptable for use with their pistols.
Even some mainstream manufacturers, such as Hornady, are beginning to use steel cases.
That said, some manufacturers still don’t recommend you use steel cases with their pistols. I’d encourage anyone interested to check with your manufacturer and make your own judgment about whether or not to try it.
The steel in barrels is generally 25-30 on the Rockwell C scale. Not purposefully soft, but of functional use steels it is definitely on the soft end of the spectrum.