While we're on the subject, I believe that the "Routledge" (sp?) bore for the .22 shotshell was a Remington patent or trademark not used on other smoothbore .22 makes. Not sure how it differed from the others, perhaps some kind of taper bore or "long choke."

I used a Remington 510 smoothbore for finch/sparrow control in a seed processing plant I worked in in the 1950s, but don't remember it being marked "Routledge," so this barrel may have been only used on the more expensive models like the 121 and 241.