Cannot locate serial number on Westernfield M822 (.22WMR)

I have a WesternField M822 (.22 Magnum - W.M.R., equivalent to a Mossberg 640K) and cannot locate the serial number on the weapon.

I have seriously combed that gun looking and it has eluded me so far... can someone clue me in as to where that S/N is located?

Thanks!
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some 22 rifles made prior to the 1968 gun control act were not required to have serial numbers ,,but i'd guess that you might find one once the barrel is removed from the stock ,,sometimes they marked the receiver under the stock line ,,or it may not have been numbered ,,sometimes there was a combination of letters used as a serial number ,,for recording in an a+d book you will have to find some kind of identifing marks weather above or below the wood line,,
bigcurt