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You have an early Grade I FN (which made all pre-1976 Browning Auto-22's) Auto-22, designed by John Browning - in somewhat less than pristine condition.
It could stand some (gentle) cleaning, especially around the rear sight (temporarily remove the sight for a detailed cleaning).
The SN's most likely stamped into the face of the receiver, only viewable after the barrel's removed/taken down, by sliding the little forarm latch away from the receiver, and twisting the barrel 90-degrees while holding the bolt back (grasp the rear by the receiver, NOT by the buttstock, or the stock WILL crack).
You can check recently successfuly closed/sold gun auctions for "Belgian Auto-22" for one in similar style/condition to find out it's current value (How much someone's actually been willing to pay).
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