Larry,
In my experience they were typically UNDERBORED, tight bores and chokes. I wondered about that, I have never seen a 20 marked 16.
I don't have bore measuring gear for smaller gauge guns, and a quick spot with my dial indicator was inconclusive, other than the left is tighter than the right, at the muzzles. I'll take another quick look today. I always get a better feel for a guns choke from the patterning board vs the bore gauge, at any rate.
Something to keep in mind-the serial number clearly indicates a gun that was ordered. SPC stands for special length short barrels, and if Mr. Customer wanted, he could have specified tighter, or, looser bores. A gun marked SPL would have special length long barrels. Modern Darne chokes are also typically quite long, perhaps .001 or .002 per inch of barrel, coming to the final constriction at the muzzle. They were bored and polished lengthwise, and the crack about Monday or Friday guns on my part is flippant, as they were very proud of the care and finish on the bores.
That is all I've got, today. I'll know more after a patterning session.
Best,
Ted
