This would be possible. He could make rechargable ammo but it would have to be recharged by someone who had the prerequisite knowledge of enchanting an object. I am assuming he will be buying the material from his world. If he buys 25 points of material he can make 20 rechargeable bullets. If he buys 45 points of material he can make 50.

I would say 3IC weeks (since its almost 2 to the next platform when materials would come and a week from then if he has been working on the theory/figuring out in those two weeks). Does that sound fair?

With a bit more experimenting he could make them to hold offensive or defensive spells but nothing too high powered.