Hi Deltastrike,
I've found a way to make that silencer fit on the 3 lugs flash hider!
This is the silencer(King Arms QD MP5 Silencer, #KA-SIL-25):
For your information, I've fitted it on an ICS MP5. So I don't know if this will work on TM/CA/JG MP5's.
Anyway, what I did is I sanded the flash hider. The 3 lugs are too large to fit in the 3 lugs plug of the silencer. Here is a pic of what to sand:
I also had to shorten the flash hider since it was too long and it was rubbing at the end of the fitting of the silencer.
Since I've sand the flash hider, I've repainted it. After a few installation of the silencer on it, some paint chipped away. You can see where it is still rubbing and those are the places you will need to sand.
So, I hope this helps. Here's a pic of the silencer fitted on the MP5.