Remington 1100 Shotgun Serial Numbers - Meaning

[Virginian]

I do not have my research materials to hand, but the following is true as to serial number suffixes.
V = 12ga. standard 2-3/4" frame/receiver
M = 12ga. magnum 3" frame/receiver
W= 16ga. 2-3/4" frame/receiver
X = 20 ga. 2-3/4" frame/receiver
N = 20 ga. magnum 3" frame/receiver
K = 20 ga. lightweight 2-3/4" frame/receiver (LW)
K = 20 ga. lightweight 2-3/4" frame/receiver (LT)
U = 20 ga. lightweight magnum 3" frame/receiver
J = 28ga. 2-3/4" frame/receiver
H = .410 3" frame/receiver
The serial number prefixes began with L in 1968 and go up alphabetically from there, but did not change every year. I don't remember where RS fell/falls.
Your 12 gauge, isn't.

[Virginian]

I have seen a lot of Remington rollmarking "one offs", but they have usually been pretty good about serial numbers. A 'K' does not suggest a 20 gauge, it is supposed to be 20 gauge lightweight. If you have a 12 gauge with a K at the end you have a very unusual animal. I'd like to see a picture.