Lozart

This. And not just because he said me. To be fair if you're just looking for a colour change then you're right about rubbing it down first - go for a final finish around 600 grit, superfine sandpaper will be too smooth fop the paint to grip properly. I'd make sure you get all the blue off, down to metal if you can but it's not an absolute must. Then get thee to Halfords and buy some grey primer (you may need to get plastic primer AS WELL not instead of for the plastic parts) and some matt black paint. Primer first then colour but work in light coats. DON'T try and get full coverage in one go or it'll run and look shit. FOLLOW THE INSTRUCTIONS ON THE CAN. If it says allow 30mins between coats then do it. It's not rocket science but if you want a good result, don't rush it. If you want a more "gunmetal" type finish, once it's black grind up some soft pencil lead with some sandpaper and rub it lightly over the black using a bit of cotton wool. You'll get a nice grey, metallic effect. Seal it with some matt clear coat (PlastiKote is good for this).

I'd suggest taking it somewhere else. If the guy said it was fixed last time and it's still exhibiting the same issue then he clearly didn't fix it properly the first time. Initial thoughts personally are - what else has been done to the gun? Is the motor adjusted properly? Has it been shimmed too tight? a 7.4v LiPo shouldn't be drawing so much current as to blow a 25A fuse all the time unless the gearbox/motor isn't standard.

...and there's your problem.

Get the ASG B&T one. It's exceptionally good and much cheaper than the Marui one. I takes standard batteries so just buy a set of rechargeables from Maplin and Bob's your uncle.

Did you take any pictures?

If it ain't broke, don't fix it. Simple. You'll have to take the whole assembly out anyway and it really is a simple job to fit a new one. Equally if you're utterly ham fisted you'll potentially end up screwing up both. It's your choice of course, personally I tend to swap out the hop rubber for a Prometheus purple one as a matter of course but that just because I prefer them. If there's nothing wrong with how your hop works now, there's really not THAT much you can do fitting a new barrel to screw it up completely.

While much of what SD says makes sense and is borne out of a vast amount of time spent desperately trying to get crap guns work better do you actually NEED to change your hop up? Why do you think you do? Also - what make is the gun? Also - gearboxes are not all the same, AKs generally use what is known as a V3 gearbox, M4 style guns tend to use a V2, M14s use a V7 etc etc. Beyond that not all V3 gearboxes are the same as each other. They're pretty similar but there's always some subtle differences - quality of gearing, size and type of bearings etc.

Not strictly true. In real guns, yes but not in airsoft. Potentially better accuracy but range is more a function of the hop up than the length of the barrel.

Yes.

Krylon should be fine as long as the current finish is sound. If not, rub it down to bare metal then primer and matt black car paint from Halfords.

A good polymer gun is almost always stronger than a cheap metal one. That ICS should be fine though.

LiFE is fine.

I'm pretty sure nobody has tried it for the very reason that vape boxes are starting to come with LiPo batteries. They're just better.

Sound like it to me. When you put the mag in do you hear the BBs release and start to feed up? Might just be misaligned somewhere.

I've been pretty lucky really. Much like the OP I bought a cheap assault vest (Miltec Molle one IIRC) and then decided I wanted a chest rig instead. Fortunately a WAS 901 with a back plate came up on ebay for £70 and I've not looked back since! Endless sales on the UKT page have kept me supplied with pretty much all the pouches I've ever needed too.

This is a good article about travelling with Airsoft stuff http://blog.tsa.gov/2013/07/tsa-travel-tips-tuesday-traveling-with.html Mostly US info (it's from the TSA blog) but applies here too. Guns should be fine in checked luggage but you MUST check with your airline. Anything that looks like a grenade is an absolute no-no.

I have the G&G SCAR L and it's great. Whether or not it's "best" is subjective but mine's great. I have added a BTC mosfet which has drastically improved the trigger response though.

I assume it's just an ivory coloured plastic?

This. If you pay more than £20 for a full set with all three pairs of lenses and an unused anti fog cloth all in a carry bag then you've paid over the odds.

Quick change springs are far from "standard".

Fair play. Seems there really is one born every minute :-)

Which I'm sure he'll realise when it doesn't sell....

It's his prerogative. What he paid for it and what its worth aren't necessarily linked...

Or just check for standards markings....

Fair play. It happens a lot though, I see loads of people wanting hundreds of pounds for an otherwise stock gun just because they've paid full whack for genuine Magpul or CAA furniture. Maybe try some of the real steel shooting forums?