under law you are not allowed to buy weapons under 18 years of age. Although if your friend is over 18n then he can buy the weapon for you and give it to you as a 'GIFT'. Or you can use your parents names and ask them to purchase it.
you may use a gun that is brightly coloured out in most fields and i suggest that when you go skirmish, you always keep your belongings and weapons near to you. As they are very easy to falling and getting lost in the act.