Howard, H&R made some 221s 30-40 years ago, I saw one on eBay last year, the caliber stamping was factory. The 221 brass is larger than 22 hornet in all respects but one: Case length for hornet is 1.403 inch, fireball 1.400. I suspect that difference is well within manufacturing tolerances. I've been thinking of getting an extra hornet barrel, rechambering to 221, and giving it to a friend who has an old Remington XP100.