It's a weird one with King Arms. Their premium stuff is really nice - at least the couple of KA blasters I've had hands-on with, but in trying to compete in the low-end market, they made some epic compromises with the Ultra Grade.
Mould lines everywhere, upper receiver that bulges out in the middle, Plastic buffer tube and charging handle etc are just the things that stuck out to me.
I hear the Gearboxes, whilst outwardly featuring many of the same internal gubbins as their premium offerings, have nowhere near the love, attention and QA applied to them in the factory.
The Ultra Grade platform is also used for the Tippmann Recon and some of the CAA-branded stuff from ASG.