Crunchmeister is absolutely correct, the DPMS M4A1 is MADE by JG; it is not a JG clone. As such, the myriad of aftermarket parts is astonishing. The gun is made for and distributed in North America by Palco Sports in Minnesota. Its a good, solid M4 that should last you many, many thousands of rounds. The internals are identical to the non-clear JG/DPMS M4 models.
As far as support goes, if you have a problem contact the retailer. If they won't help you out, call Palco Sports and work with them directly. They have a great track record of taking care of people. Good luck with your purchase!