Contact Circle Fly. If they don't make them, they would know who does. I doubt anyone is producing them as the 16 gauge is an almost obsolete gauge, which began dying when they brought out the 20 ga. Magnum shotgun ammo. You can load a 12 ga. down to 16 gauge performance, or load up the 20 ga. magnum to do the same. That is sad, as the 16 gauge is a good gauge for all kinds of hunting. If you have a BP shotgun in 16 gauge that is in good condition to be shot, you are a fortunate man.
I just looked at Google on 16 gauge Wool Wads, and it appears that you can make your own, and buy the wool fabric to make them, but I didn't see any commercial source for them. I do know that Circle Fly makes 16 gauge wads, but the ones advertised are the cushion wads, card wads, and OP wads, all made of paper, and not wool. Get a link and phone number for Circle Fly on the Member's Resources section at the top of the index page for this forum. Ox Yoke used to make wool wads, but I understand that a new company has taken over that production, so you might have to do a little searching to find out if the new company is making wool wads in 16 gauge.