Craig: is that .145" MWT at the
forward end of the chamber for 12g or your 8g & 10g boomers?
I believe you'll have a hard time finding a 20g Parker with that end of chamber WT, and few 2 or 1 1/2 frame 12g.
Lots of numbers here
https://www.doublegunshop.com/forums...=615160&page=3
More Parker numbers here
https://www.doublegunshop.com/forums...=615160&page=6
More Smith numbers
20g No. 00 Armor steel Smith .088" L and .090" R
16g No. 00 Armor steel Smith .096 L and .105 R
16g No. 0 damascus Smith .108" L and .102" R
12g No. 4 chain damascus Smith .110" L & .103" R
Threaded Mode