Rubber Band is positioned to take up minimum room and go around the shot area. It is meant to be a band small enough that the orange connector will retain itself but large enough that it won't cause friction on the head of each ramrod enough to fail the cocking.
Grey Connector stops the orange connector perfectly so only one arm hits the rod.
Orange Rods are only example rods. Ignore them and more pay attention to the rest of the trigger.
Gatlings (gatling guns) require you to put a white or longer rod on the open side of the orange connector and move the rubber band so that it holds onto the newly placed white rod but is still hitting the orange connector under it. It had never been tested on gatling guns (by me) but assumingly reduces barrel friction as it fires.
Hope you like it! ~LvNo1000
Feel free to comment as always.
PS: is probably took you longer to read this than to build the thing :P