Is your VFC Scar Gearbox Locked up?
 

Mine was.

Hadn't used it since my last game about 2 weeks ago. Went to test fire since I'm heading out in the morning. No Dice. Motor sounded like the little engine that could, until I opened it up to find this:

http://i.imgur.com/lqzEvwN.jpg

The hex key portion of the tool located in the faux gas block had come loose, and some how made its way down into the spring of my gearbox, causing it to lock back when the motor engaged the gears.

I honestly have no idea how this happened. Thankfully nothing was damaged and I was able to recover the tool and save my gun. The stupid part about this was that the ARL was no help in releasing the spring since the tension was so great. I had to fully open my gearbox to get this sucker out.

I'm inclined to say that there's no way it got there by itself lol.

At least it was a simple fix.

WTF? That tool is at the opposite end of the gun!

Well the gas block, which holds that metal hex piece, opens into into the upper receiver. So I'm guessing it came loose, rattled around inside the receiver until it made its way back to the gearbox. Not impossible, but highly unlikely.

It kind of made me laugh.