I don't recall what year those catalog pages are from, but I'll do some digging for you when I get a chance.
This weekend will be unpacking tools and (hopefully) finally setting up my machine shop here on the ranch.

Jug-choking is the 'old school' shot-column control, and it's been used as 'trade secret' for ages and ages, even up to modern 'race-gun' shotgun tuning by guys like Hans Vang.

Cheers
Tinker