If it has to have a silencer, and be accurate i would also recommend the 2240, nice and cheap and you can really customise these babies over time, ive had some real beauties in the past. Can i also recommend you and your son take a look at the UBC for fun competitions
www.umarexboysclub.co.uk this will get you too our forum, become a member and join in the fun.
Word of warning pistols can get very addictive, one is never enough or even 31 lol, you have been warned
Happy Shooting