Is it ok to shoot an air gun (also known as a "BB gun") to knock over cups on Shabbos?
I can't think of any reason to prohibit it.
while an air rifle may not have the qualities that a real firearm possess in function it can still be used for the same purpose. What I mean is an air rifle can and many are used for hunting small game such as birds, squirrels, and rabbits. granted someone who is keeping shabbos is probably not going to be hunting the fact that it can be used for things not permitted on shabbos would make it muksa. To make a comparison even if one doesn't normally watch tv during the week the tv remote at someone elses house would still be muksa even for you. In addition o the issue of muksa I don't see using an air rifle as an activity fitting for shabbos