It is essentially the CONDOR valve, only the entire barrel moves to cock the weight and slides completely back
It is way overdone, but since getting a severe virus and having to reformat my hard drive and internet was not working, all I had was paint... so I spent it all that time on making this drawing

It is pretty much self explanatory, I think it would work rather well, assuming you could find a way to fit it all in a proper enclosure.



