You could also get some of the super colibri .22 - I tried some for the first time this past weekend and was absolutely amazed at how quiet they were...literally quieter than a BB gun. Shot them fine out of a Ruger 10/22 - you may have to put a 'real' .22 in the bottom of the mag so the colibri's will feed.
They weren't enough to cycle the action but we were actually hitting a steel plate at 100 yards with them (with about an 8 foot drop of course!
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