Identifying H&R 922

[120mm]

I have an H&R 922 that is missing a cylinder pin and a mainspring. When I looked up replacement parts on http://www.e-gunparts.com, they list 5 different cylinder pins for the H&R 922.

263340A Center Pin, Blue (AM25510 Series & On)
263180 Center Pin, Blue (K Series To M), NI
263210 Center Pin, Blue (M Series To N28255), NI
332690A Center Pin, Blue (N28255 Series To V)*
263290A Center Pin, Blue (V Series To AM25510)

My serial number is 143xxx. There is no indication of the "series" of my piece. Anyone have an idea of how to tell what "series" my piece is, and what bearing this has on center pins?

Here's a pic. Thanks!