You should remove the inverted commas "" from the script and add them in tne init field :
[this,"ak47","ak47"] exec "Weapon.sqs"
and :
Weapon addWeaponCargo [_weapon,1]
I did that, and it worked... almost : at first, I was able to grab the weapon (the big thing being that it does appear, now...), but now I no longer can
As to the ammo, as I can't grab the ak47 anymore, I can't say whether it is loaded or not... :-\
Hope this helps anyway.