OK, I got both guns out of the safe(s) again.
My original assertion was that the Sweet 16 is built on a 20 gauge receiver. If the 16 predates the 20, then it must be the other way around.
The following measurements tend to support the assertion that the Sweet 16 and 20 ga. A-5's share the IDENTICAL receiver (at least before the gauge specific machining).
Guns in question 76Z-88xxx (1976 20ga.) and 5S-36xxx (S-16, 1965). I originally claimed 1963... sorry, it's from 65.
My advisors are Mr. Starrett and Mr. Stanley.
Mr. Stanley says both receivers measure 6 3/8" in length from the back of the mythical 'hump' to the front.
Mr. Starrett says:
Height top to bottom just in back of the closure button - 2 9/16".
Width same place - 1 9/32". Width across the rounded part above the bolt - 1 7/16".
Height just in front of the trigger including trigger plate - 2 3/4".
These measurements are indentical on both guns.
Both of my advisors claim the tang length is also identical, although the distance between the tops of the tangs varies very, very, slightly probably making stock interchange very 'iffy'. Stock interchange on A-5's in general is known to be 'iffy'. There was some hand fitting (imagine!) on these.
So... my advisors have a different opinion on this than some other advisors.
Will someone kindly measure a standard 16?
As Nimitz radioed Halsey "The world wonders".