[Bishop54]

Consider me baffled. My father just came across this flinklock pistol and no one seems to be able to tell him what the device is for. When the frizzen is closed and you push the button on top of the frizzen it allows a small plate to remain over the pan. When you re-close the frizzen it works like a normal frizzen where sparks get thrown in the pan the usual way. What could this device for? Is there anything else you can tell me about this flintlock? Here's some pictures to help with the identification. Thank you for your help gentlemen.