Gary, I do not think your theory on the use of alpha prefixes is going to work because Parker Bros intermixed O, A, and B throughout the serial number run data I have from serial 19 to serial O2696. There are Os with 2, 3, and 4 digit serials, As with 3 and 4 digit numbers, and Bs with only 4 digit numbers. These are all back action data and I have info on 51 guns. Hope this is helpful. Bill

Yes Bill, It puts to bed my theory, Just trying to figure out why? There is no rhyme or reason for the way they did it, Bill what is the highest serial # back action you know off? Gary

i got the 11 ga out of its corner the serial no is 01500.....charlie

Gary, the highest back action gun I have data on is O2696. The highest B gun is B1734 and the highest A is A1720. Bill

This is B1217. This would make a good Parker Pages article, if someone had a good theory

Bill, I agree with Mills this would make an interesting and ongoing discussion in the Parker Pages, Who know maybe we can get to the bottom of this mystery, I will check all my guns and post any prefix guns, Gary

Didn't Parker have independent contractors building guns back then? I wonder if each contractor had a different mark? Could it have something to do with frame size? Grade?

As far as I can determine, back actions were built with frame sizes 1 and 2. I think I have one of each.

I bet you the letters have something to do with the contractor who worked on the gun

I checked my guns today and here are the numbers, B 2349, B 258, 0 29, B 1147 and the most interesting T 4412 The T is in capital letter could be twist but it is inline with the numbers and the same size?go figure, Gary