Kammer: Ruger does tend to make firearms in intermittent runs. I noticed the .450/400s drying up on Gunsamerica and Gunbroker, so I pounced.
Robert: No. 1s in .303 and .450/400 would just about cover all matters, no?
But what fun if Ruger would chamber in .318 WR or .333 Jeff Flanged! It would no doubt be least expensive to buy a No. 1 in a smaller caliber and have it rechambered and rebored.
Now off to Turnbull's site.