H&R only makes one stainless rifle offering currently, the 45-70 Ultra Hunter, all the rest of the SS firearms have been discontinued.
They've been offered in 223, 22-250, 243, 270, 30-06 and 444 Marlin. One member has stated he had a 22 Hornet barrel, but I'm inclined to think it was a Handy Gun II which was electroless nickel, not SS. H&R may still have some stainless accessory barrels in stock tho, I'll see if I can find out.
Tim