I don't have a 20ga & only one 16ga. The 16 @ 6 3/4lbs is not a particularly light one & it only measures about 1 1/16" pin to pin. I have 12ga's with pin spacings from 1 1/8" up to about 1 5/16". This one sounds like a light 12 to me.
Rich is correct about it being a two hook gun. Also I don't recall seeing a dog on the plate of an F grade except on these early ones. This would all appear to validate the age given.

Last edited by 2-piper; 03/30/11 09:54 PM.
Miller/TN
I Didn't Say Everything I Said, Yogi Berra