Your story is curious. Did you ever find out what the source of the AUG was? Where did it come from, who upgraded it, etc?
I recently dealt with an ASC user with a very similar story to yours. I don't know who the store was that he dealt with, but this is as far as I know:
This user sold (traded?) his fully tuned paintball markers and bought (traded?) a Steyr AUG from some surplus shop (again, I don't know the store.) He was told that it was fully upgraded with a Systema FTK and shot 400fps.
Upon taking it home, he discovered that it wasn't shooting right, and the gearbox sounded excessively loud.
He brought the AUG to me to have a look at it. The gearbox sounded *okay*, but nothing too excessive. It just sounded almost like how a high velocity gun would sound, if not a bit whiny. I figured a motor height adjustment would sort that issue out. I started looking at the feeding issue with the inner barrel. I took out the barrel and looked inside. Right away, I noticed that the hop up rubber's lip was warped completely out of shape and blocking the exit, preventing ANY BB from passing through. It was a jamming point.
So a note was made to replace the hop up rubber and I moved on to the gearbox.
I took the gearbox out to look at the motor height and right away, I noticed a tiny metal disc attached to the motor magnets. I didn't recognize the disc, so I just put it aside. It looked chewed up though. I turned the gearbox over in my hands and noticed that it had bearings installed... or what was left of them. 3 of the 6 bearings were blown to shit, with the spur gear barely hanging on. I'm surprised that the gearbox was still able to cycle, but that was the cause of the excessively loud noise. After checking the spring, I figured that was the cause of the blowing bearings, as it clocked in at almost 390fps. 6mm bearings are meant for no more than 350fps setups. Thankfully, the teeth on the gears weren't totally borked from the blown bearings no longer supporting the gears and were easily salvaged. And luckily, none of the ball bearings had gotten between the gear teeth and caused any major damage.
On further inspection in to the gearbox, I noticed not even ONE shim was used against the gears. No wonder the bearings blew!
Anyways, I replaced the bearings, degreased and regreased the whole gearbox, properly shimmed the gears, replaced the hop up rubber, readjusted motor height and the gun was firing like a dream again.
He got the gun at a decent price, but it was a perfect example of why I would never recommend a newbie to buy a second hand gun, unless they have someone experienced with them to look over the details. A new user unfamiliar with how a proper gun should sound and/or operate may end up continuing to firing a non-functional gun, hoping to figure out what's wrong, and in the end, cause more damage through excessive operation of malfunctioning internals.
Last edited by ILLusion; December 18th, 2006 at 17:00..