By jove, that does look like a spring loaded sliding latch, doesn't it? Funny that they were with gun cleaning supplies.The larger part may be a lock part. What looks like a firing pin is a spring guide. The coil spring fits over it and bears on a pin that goes through the large elongated hole to force the latch outward. The smaller hole probably had a screw or pin to hold the part in place in the lock.
Jim
I had thought maybe from some goofy flint/cap lock but locks/latches seem more like it and given your reference to the cross contamination of lock-firearms maintenance, things seem a bit clearer now.Mmmmmm?
Hate to count how many door locks I have repaired over the years using my gun cleaning tools & supplies.
Door Lock parts do seem more likely then gun lock parts though.
They aren't well finished enough to come out of a gun, complex enough to use parts like those.
rc