I'm going to the US to shoot in a competition in a couple of weeks time, and there is a substantial prize table...

Now the hypothetical bit.... in the very unlikely event I should get a sniff of anything on that table, (as long as its legal to own in the UK), how difficult will it be to bring a firearm home..?
E.g. I have a slot for a .223/5.56mm rifle on my FAC. If there is a .223 bolt action rifle on the prize table, would it be possible or easy to bring that back into the Uk as a personal possesion..?
My Google Fu is poor at the moment, and all I can find are references to "importing", which I take to mean for commercial reasons, but what about for personal use..?
About the only relevant reference I did find said that UK Customs should enter it onto your FAC as you enter the country, although apparently they're reluctant to do it..??
This reference also mentioned paying the VAT on it... but what if its a prize..??
Bearing in mind that I'm coming home 2 days after the comp, so won't have time to go through a complicated form filling / US export licence application process, in this (hypothetical) situation, would it even be worth considering..?
TIA
Daryll.