it's a grey area. The whole full-auto thing is weird. I'm pretty sure some of the toys fall into dodgy legality. It's just not acted on. Think about it, how many players have a marker capable of full auto? it's quite a few, you wouldn't use it in tournaments, but I bet everyone has tried it out. If it's not legal to own one in he UK, how many players are breaking the law?
How about a definitive answer? is full auto illegal or just against the rules? if it's illegal then so are a lot of high end soft-airs. Plus any marker with selectable fire rates. How many players have bought US markers? how about RACE, Bushmaster etc.... Where do we stand? Are we getting away with it because the powers that be don't fully understand the implications of the firearms act? or are we in a legal grey area? E.g. if a player is stopped in his car and the PC finds a marker in his boot (trunk), he'll probalby accept "it's for paintball" and no more.
By the letter of the law, I believe full auto markers are illegal (5.1a of the firearms act) we just haven't had anyone charged for it yet. As far as I can see, using/owning a full auto marker could land you in as much legal trouble as owning an Uzi. (ten years in prison).