From my understanding of how his powers work he should be able to charge things in a single touch. So he could just have a custom firearm that would allow the ammo to glance his finger each time it’s loaded, allowing it to be charged. It doesn’t even have to be a actually gun, since a BB gun, hunting slingshot, or crossbow would be just as good.
In the comics he actually gets something like this, might happen in the show pretty soon. Won’t be too specific bc spoilers.
He’s only a teenager and can’t buy a gun yet
The real question is how do different materials and their attributes affect their explosive power? For example would denser metals explode with more force, if he made little balls of already explosive material would they be even more powerful?