If your Fowler is unchoked you can shoot steel in it if you use a shot cup. It will make your pattern a little tighter as well. If your gun is choked I would go with Bismuth.
I have a shot maker I inherited from a friends estate. It uses rods of lead, slowly melted with a stationary propane torch, through a very small nozzle. The shot drops into a can of water. I make my own tin shot with this device. This contraption has no label, or any other markings, and I have never seen another one. Somebody told me there was an article about them in an old Buckskin Report, but I've never been able to find it. The shot turns out looking like little raindrops, but the critters can't tell the difference.
Hungry Horse