So this part flies out of my KSC G23F...
 

And it looks like the front part of this:

http://www.wgcshop.com/pcart/shopper...G18-24_cat_KSC Parts

I suspect that this is the KSC floating valve.

The part is broken at the stem. I have the front part with fins on my desk and the broken base still sitting inside my loading nozzle at the moment.

What caused the failure? Should I simply replace the part with a OEM KSC one or order the Firefly rocket valve?

For reference, I have a FMU G23F with stock valves, reinforced/stiffened recoil spring guide set, stock hammer spring. And a steel mag catch, if that makes a difference.

What kind of gas were you using in it, and had you been keeping up with your regular maintenance?

Apparently this is happening in many peoples G23F's. Very strange, I have owned several of the full auto Glocks made by KSC/KWA and never had the stock floating valve break, even using red gas (ET1600). Get the Firefly floating valve, it is a good piece, although, the winged tip may blow off like what happened with your stock one, it still works fine. I have 3 KSC G19s with the firefly floating valve, they all blew the tip off but they all shoot 100% with the tip gone.