I am trying to find the date of my BL-22. I have looked on the browning web site, but my I cannot figure it out. 1st, my serial # is on the bottom of the receiver, the online manual says it should be on the right side.

Its made is Japan Grade I, I think it does have engraving. The serial # is 70B31XXX.

Any ideas?

No expert here but looks like 1970 as the year of mfg. Product code is B. Later on they switched product codes, 127 was plain gun, grade 1 was 126, and grade 2 was 226, according to my old Browning dates of mfg. book.
C.G.B.