I'll take a somewhat wild-assed guess. A mainspring cramp ( not clamp) is a little tool used to properly compress a gun's mainspring for removal or replacement. So I'm guessing this could be a built-in feature to keep the spring in a compressed state to safely permit in field servicing or replacement of a broken striker.
Some people would probably wish to carry a mainspring cramp in a gym bag, along with their white cotton gloves and other myriad accoutrements, to gun shows. This is because we all know most gun show vendors are very receptive to anal tire kickers disassembling their wares and pouring oil into the ribs.
If my reply is not censored, it should show up by Tuesday or Wednesday. By then we should know if I am right or not.
