There is NO commercially available tang peep sight, made specifically to fit a Browning BL-22, most likely due to both lack of demand, and an almost non-existant rear tang to secure one to.
A determined experimenter could most likely, through trial/error, fit one or another of the various tang sights from Taurus, Lyman (#2), or Marble's.
If one is used that has a stem with the proper rise, the issue height front sight will zero.
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