Starline is making it now so that’s a real plus. When I bought mine (94 Win with bad finish but great bore) it was in the middle of the last banic and there was no brass to be had. I made my own by blowing out 30-30 and also by buying some 38-55 I found at a gun show. Neither can be loaded up to full 375 potential, but as I was mostly interested in shooting cast bullets at moderate velocities it really didn’t matter. I have a full box of Starline 375 brass but I’ve never even opened it. If I want full power there are other rifles that are a lot more pleasant to shoot than a straight stocked lever gun with a hard rubber buttplate.
I wasn’t really looking to add another cartridge to my mix but the gun was pretty cheap and I already had the bullet molds.