Originally Posted By bradpierson26:410 barrelWhat kind on cocking piece could you use for this?
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After figuring out how you'd want to breech it - threaded cap or any other choice - you could use any number of firing mechanisms.
The classic pull to cock and push the button to fire is an option but so is the more cheap/dirty/modern pull and release to fire.
It really depends on how much work you want to put into it. I suggest looking at the old patents and going from there. There are literally thousands of firing mechanisms in patents old enough to use freely - and most have excellent drawings.