No need to PM.
The parts list is in the post. And it's already dumbed-down about as far as it can go. 3 cheap chips, a couple push buttons, some LEDs and resistors, and a 9v battery, and something to mount everything on or solder to, and done.
I'll "help", but I'm not going to build it for you.
Google the part numbers for datasheets, match up the symbols in the picture to the datasheets, wire up as such.
The 4017 is a 'decade counter', eg. counts in groups of 10's. Starts at one end, gets a pulse, works its way to the other end.
The 4013 is a 'latch', basically keeps track what's going on...either shooting, or reloading.
The 7408 AND gate is there to let the trigger pulses thru.
Power up the box and the decade counter is set to zero, the AND gate won't let trigger pulses thru, the latch is set to reload.
Click reload, the latch 'remembers' you hit reload, the counter is reset, and the AND gate lets trigger pulses thru.
Click the 'trigger', the decade counter counts up by one.
When it gets to the end, the last LED sends a pulse to the latch which resets it, shuts off the AND gate, which will no longer let trigger pulses thru, and since the counter is at the end, all it can do is go back to the start. The trigger pulses won't do anything because the AND gate won't let them thru. Have to go back to the "Click reload" step above.
Stand by one...