King Arms 556 Shorty Faulty

[GroverA 125]

I've used the mentioned AEG once before and it worked fine, went to take it to a skirmish today and it gave up on me. At first, the chrono was coming up at <200 fps, and I was told to try changing mag. Upon doing so, the AEG would no longer fire correctly. The majority of BBs would not leave the barrel, and those that did literally fell out the gun, reaching about 6 feet of range. At first we figured that it may be something to do with the hop unit being on, so we dropped it to nil and tried again, to no avail. Then we tried using different mags (I use Ares Pmags as they are the only ones I have never had trouble with, others would not fit and the provided mags wouldn't feed properly) to the same result. Afterwards, we figured that the problem was that the hop rubber had been killed, and with my friend and the site staff saying that Sigs are as hard to get into as Fort Knox, we decided to leave it at that.

After getting home, with the right tools, we finally managed to get it open and was surprised to see that the hop rubber is undamaged. After two hours thinking what could possibly be causing it, we gave up and reassembled the AEG. It appears as though something is blocking the BB from moving forwards, before it enters the barrel, as placing a BB into the chamber resulted in it seeing resistance being moved forwards, but past that original resistance, it would slide straight down the barrel. It looks to be stopping right in front of the mag feed, but we couldn't discern whether it was normal for this or whether something was up. The site were saying that it always looked like the hop was on full, but it had been adjusted by themselves to confirm that was not the case. Got to the point where we're absolutely clueless and with this being my first RIF and barely having 8 hours of use under its belt, I'm unsure what to do. Any help would be much appreciated.

[steven_191]

Re: King Arms 556 Shorty Faulty

I had this with an mp5 the other day. I believe the problem was a ridge on the nozzle around the middle of its length, that was catching the back of the hop unit causing no seal and therefore no pressure down the barrel so the bb just rolled out.
So I would check the nozzle is fully seating into the hop. What part exactly is the problem still needs looking into.

Hold the gun upside down, look into the hop, watch the nozzle and see if it moves fully back and forth while firing.