Buffalo Bore or Garrett would have been my preferred brand for the 45/70. But Ammo is slim pickins lately.
I picked up Underwood ammo. 305 grain penetrator slug at 2100 fps. I also use underwood 220 grain hard cast coated bullets for the 10mm. They are running right about 1300FPS from my 7 inch barrell. Not perfect but pretty decent for a semi-auto pistol.
For the 12 guage I keep some Brennecke black magic slugs. They are insane. 602grain slugs at around 1500fps.
Its almost always the same companies doing it. Yet people continue to use them even during normal times. I heard a rumor that Federal was shipping direct to customers in states where they can. I haven't verifid that yet though.