At one times years ago Corbon loaded the soft Rem. 158 gr. LSWCHP in a +p load that cranked a true 1K fps in a snubby. I believe they used gas checks as well. I asked Mike, their sales mgr., why they dropped it & if I recall he said they had a Helluva time in loading the extremely soft bullets w/o damaging them. Of course, the general move away from .38 sales to semi-auto loads probably didn't help.

FWIW, Undwerwood uses the same commercial lead bullet that Buffalo Bore uses for their loads as cast by Rim Rock:

g/ch .38/.357 mag 158 gr. SWC-HP per 100/ in a plastic ammo box - Gas Checked Cast Lead Bullets - Premium Bullets