@Jaylordofwaargh is right used is used.
But it doesn't perform exceptionally well though does it because you messed with it and couldn't get it right which is shocking you being a "professional tech" and all.
What advert should say is:
G&G TR14 used and abused.
I took an average gun and diy teched it until it was worse. Fitted a basic Titan mosfet that will only cost you £45 to use properly. Put in a bunch of upgrade parts some of which are notoriously fragile but I have supplied the originals for a real tech to fit when it breaks.
So please give me more money than standard gun costs so you can have the enjoyment of this badly built piece of crap costing you more money and maybe ending in a youtube tech vid titled "look what some ham fisted monkey did to this poor gun."
Postage and paypal fees included.