I think the old 20s were made on a 12 gauge frame...
Thankfully, this is incorrect. 12s and 20s had their own respective frame sizes. The 16 gauge 870 guns were built on 12 gauge frames. Likely this is where many get confused on the issue.
I'm am pretty sure all Wingmasters 20 gauge and up were on the same frame size (12 gauge) till the late 1970s. I'd be willing to bet a beer on it
. Not sure what year the 28s and .410s came out on their own smaller frame.
