It is possible to fit into VFC HK416-M4 GBBRs and also possible to fit into WA-system. You need to cut down only of leg and file the other one a bit. In VFC you need to file two0 line to let it fit into the barrel extension.
I got much better result with this chamber and the GHK's rubber in VFCs and WA-systems.
I highly recommend to use this setup with a good quality AEG-type inner barrel!
