Stecker

[GIO]

Originally Posted by fernando

Gio, you probably mean Stecher, also called 'hair trigger', an ingenious mechanism that drastically reduces the pressure/tension applied to the actual trigger, invented by a Munich gunsmith in 1543 ?

Many thanks, Fernando. Now I have a date and a place. I was not able to find such info by myself.
As to the other device (the "butterfly"), I apologize I don't know the English name (as for the STECHER), but am confident to obtain some info.
Thanks again for the quick answer.