There was one of the OG M82A Barretts on the wall at M4A1 that I got all gooey over.
Not for sale though… absolute pieces of shit but what a display platform. 
Just a heads up too… Select lever issues aside, I ran a few gels through the chrono with the 552 to get a performance baseline.
It was only hitting around 220FPS. 
The spring’s pretty accessible, so if you’ve got an M95 or M100 spring lying around you can throw it in easily enough when you get it back. 
If you do head up to Nambour on the weekend, drop by with that SCAR H and I’ll have a look at it for you… I can run it back down to you next week sometime.
Up to you, matey.
A few tips for the JG V3 tinkerers.
Their mag terminal blocks are a PITFA, but the gearbox is otherwise nice to play with for anyone who is familiar with V3 stuff.
For longevity, I recommend a little radiusing and AOE pad. The rest of the gearbox is pretty decent. It is 50/50 whether the blaster comes with the black end bell motor (shit magnets) or the blue end bell (neo magnet) motor. The blue is an awesome motor, paired with 13:1 you will get a very snappy semi and 25rps, and it loves it.
Cast gears are decent for cast gears. Piston is decent though worth getting something you trust in there if you are in there, Piston heads and o-rings are awesome- don’t change!
The nozzle on the JG V3 is interesting. No rubber tip. The rubber is in the t-piece, kinda backwards, only really an issue if using softer gels, but you won’t be using cheap softies on these anyway. The are a wells spec base, so changing nozzle to one with an o-ring requires serious ingenuity, lathing down a wells nozzle is not ideal. Good lube and they seal ok anyway, just not perfect over time.
Gearboxes are cheap at Ausgel, so grab a spare in case. These aren’t something I would recommend pulling apart unless you have to, but if the gearbox did go the spare is a good option to radius and aoe pad.
As a note @Friendly_Fire
Some of the shorties shipped with a full cylinder… might be your issue? All the other JG v3 need a full cylinder, the 552 really needs a ported one and not all shipped with one… because medichina I guess.
Yeah, the brief was just to sort the ambi out, but if the box’s out maybe a little more work on it wouldn’t hurt. Like you said, not the easiest of blasters to tear down and not a lot of info online, even relevant to the airsoft JG 552s.
What exactly is it? A V3? Never worked on a V3 with a separate grip housed motor before.
Not sure what happened with this one, because the ambi gears can really only go on one way… but the levers were definitely not aligned to each other. It would not easily rotate into safety without a horrendous grinding feel and if you did get it into position safety was non-existent.
All screws were loose by quite a few turns too… must have been a Friday blaster. 
Selector plate works fine with the gearbox out, safety engages so it must be a case of misassembly of the ambi gears by Wong over in Beijing. 
They are a V3, but the motor is a mid length mounted in the grip instead of a cage.
They are VERY similar to the airsoft JG sigs, so might pay to look for tips there.
The ambi is very typical of many ambi things and a bit grindy and janky on some but fine on others. The misalignment though is odd.
Spare boxes are reasonably priced at least