As I recall, a duck, a bird dog & a quail were depicted in a circle with scroll work. I don't recall which was which. A #4 & 5 were hunting scenes with pointers and quail. The 5 had a lot more scroll going up the chamber area of the bbl. I have had numerous M12 pigeon grades and some were not engraved. Back in the day, Winchester would build a gun however you wanted.
About all I know of 2pin/3pin guns is that 2 pin VR guns, with a machined "wavy" duckbill receiver ramp, are more desirable, as they were produced up to about '59 or'60, and some believe they were fitted together and the moving parts polished in place to a finer degree..equals a smoother operating gun.
Three pin guns, produced after 1959 or 1969, are still fine guns, generally have a smooth duckbill receiver ramp, but at, or close to the end of the run for pre '64, guns, and some believe the quality of workmanship is slightly lacking.
There were so many variables and ordering options from the Winchester Custom Shop, that you may find about any combination of parts on a gun, and it could be all original. When purchasing, if in doubt, consult a good reference book, or a known Winchester source, for advice.
I like them both, and the "Y" Model is also a good shooter.
I have the Winchester Special rib model, 1,795XXX made somewhere in the late 50s
A soldered rib model to compete with the 870 which was selling well.
Anything but smooth like the early guns, it shoots well.
Years ago, I read somewhere where you could pack the internals with polishing compound and cycle the action many times. This was supposed to make them a bit smoother, but it seems you would end up with a good mess to clean up.
hi gerald the pigeon grades were smooth due to the fact that the bolts were slightly convexed in the middle. the whole surface did not rub on the reciiever when cycling. ever notice when some people had thier bolts jeweld or damsend it would wear off. they all wear in smooth eventualy regards howard