Things like this often solve by
searching the forums or the faq or even the tutorials. Questions like this get answerred weekly.. and here goes again. The init line of the unit should look something like this:
this addmagazine "ak47"; this addmagazine "ak47"; this addmagazine "ak47; this addmagazine "ak47"; this addweapon "ak47"
Also you might want to go to
www.ofpec.com/editors and get the official command reference for exact string names of weapons and mags and the complete command list.