Walter,

Notice my example above is only a 4 digit number also but was drilled thru. If it's the proper 1/10" forward of center, that tells me your frame was made and drilled for the swivel initially, the serial number having been stamped off center to miss the swivel hole. That's why it didn't letter: it was not special ordered or added as an extra, therefore not listed on the invoice.

So by virtue of it not being drilled thru the number, and not "lettering", you know it can only be a factory original!

__________________
Jim
S&WCA #819