Perhaps you could look at how semiautomatic pistols with hammers work.
Their triggers are set far forward from the hammer like that props setup. They use a "trigger bar" to accomplish the linkup between the trigger and the hammer mechanism.
It´s reallly a dream to have a complete workshop for working metal. Much work to cleaning it but aluminium have the advantage of be light and no rust. Good work
Most of my tools are really wood work based, the aluminium is just soft enough for me to get by, I'd love a metal lath and a milling machine...... and.....and .... Well one day