Why does UKARA come up on all these? UKARA doesn't "approve" you. It is not a licence. IT does not allow you to do anything (in law). All it is is a cheap and easy way for a retailer to check that you come under one of the groups of people for which they have a defence in law for selling RIF's to.
sp00n, whilst you are correct it is not illegal to own a RIF, it IS illegal to manufacture one without a defence. Changing a coloured part for a plain black one such that it decreases the percentage of bright colour to blow 50% is manufacturing.
If you wish to alter an IF in such a way that it becomes a RIF (less than 50% in one of the allowed bright colours) then for it to be legal you need to have that defence, so in airsoft you need to skirmish "regularly" at a place where public liability insurance is carried for playing airsoft. Whether you are a site member or not matters not a jot. Whether you have registered with UKARA or not matters not a jot. It is being able to prove that you have a defence against prosecution under the VCRA that is the important thing, otherwise you stand to be prosecuted for manufacturing a realistic imitation firearm if you are caught.