By the serial number.
A pump shotgun.
1866 through the early 1990s
50-200 usd
It was manufactured in 1932 . http://www.marauder.homestead.com/model97sn.html
870 and 700
50-150 usd
what year was the nitro hunter singal shot shotgun 12G made.
12g-9 = 3
It is: 12g+9g = 21g
Almost certainly not. The writeup talks about the different gauges but says nothing about interchangeability of gauges and that would be most unusual and worthy of note.
The GCF is 12g.
12g is 12/14, or 6/7, of 14g.