Greg,
Here is a pic of the barrel flats of a 3 barrel set: 20/16/16.
Comparison may help.
Bob Jurewicz

Too clarify; the 20 GA barrels are 26" not 28".
Bob Jurewicz

Bob, please don’t be offended by my question -

Is this a factory three-barrel set or a “put together” three-barrel set?

Humbly, Dean





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Dean,
No offence!
Composed. 16 M/F barrels added. But, all 16 barrels were add ons.
Bob Jurewicz