My M15A4 Sportline has kicked the bucket

[NS-Airsoft-Noob]

Just an hour ago I was having some fun with my stock CA M15A4 Sportline Rifle, shooting a couple targets with rapid semi-auto fire. After going through three 85-round VN mid-caps and one 190-round VN high-cap, my gun quits on me and absolutely doesn't do anything (doesn't make a single sound) when I pull the trigger.

I immediately removed the rear stock and checked the 20A fuse in the wire set to see if that was the issue; it was still completely intact. I then directly connected the mini-Tamiya connector coming right out of the mechbox to a charged-up Ni-MH stick battery from my father's CYMA CM042S AKS AEG; I tried both of his stick batteries one at a time and my gun was still dead.

When my gun failed there was still a BB chambered in the hop-up unit; I had to dislodge it using the supplied cleaning/unjamming rod. I'm concerned that the mechbox spring might still be compressed, so I've included some pictures of the mechbox in the gun so you guys can look and see if that's the case or not:




Also, I was a bit disappointed to see that Classic Army had installed an M4-length 363mm barrel in my gun, instead of a typical M16-length 509mm barrel (I guess I got what I paid for):


Isn't using a short barrel with an unported mechbox cylinder a bad combo, as explained by MadMax in this old thread? http://www.airsoftcanada.com/showthread.php?t=18038


Could my stock motor have blown, or is there also something wrong with my stock mechbox as well?

[phloudernow]

Might be loose motor connectors that is one thing you you can check. take the base plate off your motor grip and check to see if your wires are loose. if they are put them back in and check. if still nothing it might be ur motor as died. no sounds are usually something to do with the motor or your wires.

[Rusty Lugnuts]

That spring is not particularly compressed, if it was you would see piston in the mechbox cut out not spring

[Jimski]

spring doesn't look very compressed, anyway it wouldn't matter much.
As soon as the mechbox opens a bit the spring uncompresses.

[Styrak]

The only way to figure out what's going on is to get it diagnosed or opened up by someone who knows what they're doing. As a gundoc, showing me the outside of a mechbox does nothing to help.

[NS-Airsoft-Noob]

Thanks to phloudernow's suggestion, my gun works again. After popping off the bottom plate from the pistol grip, I saw that the positive wire was loose; put it back in place and the gun fires normally again.

Sorry everyone for me jumping to conclusions; please forgive me as I'm still new to the whole AEG side of airsoft, having only owned cheap Canadian Tire and Walmart spring clearsoft before being able to afford this M15A4 Sportline with all the Christmas money I got during the holidays.

But I want to now ask, am I right that the cylinder on my mechbox is of the unported type? I have a new Madbull Black Python 509mm-length 6.03mm tightbore barrel on its way to me so I'd like to know, as I've heard ported cylinders don't work with long barrels.

[Styrak]

Yes, your cylinder has no ports in it, therefore it's an unported cylinder. Which is also correct for an M16 (510mm) inner barrel.

[NS-Airsoft-Noob]

Originally Posted by Styrak

Yes, your cylinder has no ports in it, therefore it's an unported cylinder. Which is also correct for an M16 (510mm) inner barrel.

Thanks Styrak for confirming that.

[lurkingknight]

there's nothing inherently wrong with using an overvolumed cylinder. The side effect of it will be some slightly higher velocity using heavier ammo... so if you clock at 400 with .2s, technically if everything was properly matched, you should see about 327 with say a .3 but it will actually be a little higher.

Your gun will not explode.

[Maxxa]

Have you tried putting it in auto and pulling the trigger? These V2 gearboxes are known to lock up in semi if the trigger isn't pulled right back quick enough. This has happened to me on at least 2 occasions.

[Wrath144]

Your cylinder port may also be hidden inside the mechbox.