They are a Swiss after-market item. I have seen some with a manufacturer's mark on them. Mine are just marked "DEPOSE", or "remove". I think that in a panic situation, they would blow off without damaging the firearm, but it might flip back in your face! I forgot to mention that they are primarily a muzzle/bore protector. Keeps the crud out of the barrel after cleaning.
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If it's made after 1918...it's a reproduction
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