Could he turn up pay the fee then leave the game after 10 minutes and go home?
Entirely up to the site. UKARA (and equivalent schemes) are just centralised registers of site memberships. It would be a crappy thing to do to any site that's running limited numbers of players, since he'll be taking a place away from an actual player, and not buying any consumables.
I mention this because there's a difference between legality and morality.
What I will note is that there's no age limit on the defence for modifying an IF into a RIF [edit - see below]. If you are an active airsoft player, you can adduce that defence, and there's no statutory requirement to have a UKARA number (because there's no definition of the defence in the statute, or even in the regulation that added our defence, it's in an accompanying circular, and suggestive). In plain language: if you're an active airsoft skirmisher, you can paint your two tone, same as anybody else.
Or practically speaking, private sellers tend not to care as much about defences.
Legally speaking, if I were selling to your parent, and they could provide evidence that it would be gifted to and used by an active airsoft skirmisher (of any age) then I'd be fine with it. That would apply even more if you could find someone at your local site(s) who's looking to sell.
high end rifles we want something that will last us a long time
Those things
should go together, but airsoft doesn't work that way. The cheapest CYMAs are cockroach tough, while VFCs can come pre-broken. Unmeddled TMs might qualify. Just don't expect startlingly better performance than your Lancer.
I've heard some say the age restriction part of the VCRA only applies to the sale of rifs, not the modifying an IF to a RIF part so the OP could change or paint the snot green parts.
However, I wouldn't take this as gospel as you don't want to be the test case in the unlikely event you end up in court and something tells me "some guy on the internet said it's ok" wouldn't be a good defence
Fair point, but the VCRA isn't secret and S36 (offences) and S37 (defences)
don't make any mention of age. Age
is an issue for Firearms Act 1968 S24A, which applies to the sale and the purchase of imitation firearms.
The inconsistency there is off the charts, given that there's no VCRA offence of
purchasing a RIF (at any age). Which gets to another piece of lawyer-bait, whether the same item can be an imitation firearm for the purposes of the Firearms Act,
and a realistic imitation firearm for the purposes of VCRA.
I say yes, of course it can, while other people argue equally passionately that something
can't be both a firearm (for FA) and a realistic imitation firearm (for VCRA), i.e. airgun replicas.
As you say, test cases, test cases, test cases.
But if OP is going to be sensible with his use, it won't be
his test case. And if he's not, then the VCRA will be the least of his worries as he'll be looking at Firearms Act offences first and foremost.