You're very unlikely to find anyone here willing to wreck a perfectly good gun...
http://www.tacticalairsoftshop.co.uk/ these people will 2 tone any gun they stock and are reliable but wouldent it be better to get an adult buy it then sort of permanently borrow it from them 
,you just have to persuade them to go to a site a few times to get a membership.if you need a gun quick for a ww2 game then plenty of people will lend them out just look on the kit loan thread
armoury
m1a1 Thompson,sten mk2,mp40,stg44,sterling,mk2 bren gun,lee Enfield no4 mk1,Mauser Kar98, Walther ppk,smith and Weston m10 and Mauser m712
Give me a big enough hammer and a place to stand and I could fix the world.
i'll kill a man in a fair fight or if i think he's going to start a fair fight or over a woman or.......
a problem shared is a problem halved ,but an advantage shared is no advantage at all
if a job's not worth doing then its certainly not worth doing well
If he's under 18, an adult would have to buy it anyway.