Over bored barrels

[J.B. Books]

I don't think in practice it would be much different than using 12ga gauge mates in a 10ga gun, 20ga gauge mates in 12ga etc so there should be some experience with performance on the board with this.

Surprisingly ATA rules govern the chamber, no larger than 12ga, and not the bore, so way overbored barrels are legal. See page 49.

http://www.shootata.com/pdfs/2011_rulebook_4web.pdf

[Pa SxS]

It's not only bore diameters that have come full circle. Ever look at how a Seitz, Silver Seitz, and Ljutic shotguns break their barrels open? These are all high end trapguns. They open with a mechanism located in front of the trigger guard. Sounds like Parker had a winner with their underlifter design. 100+ years ahead of the rest.