A lot depends on the weight of the fowler, and how you load it. It seem the majority of shooters tend to load their smoothbores just like their rifle, when shooting round ball. A tightly patched nearly bore sized ball, and 3F powder is going to kick, especially in a light fowler. Smoothbores were traditionally loaded with paper cartridges, that don’t use a patch, or a ball close to bore size. They also shot courser slower burning powder, which generated less recoil. Native Americans did away with the paper cartridge, and simply dropped an undersized ball on top of a heavy charge of slow burning powder (1F or 2F) and covered it with a greased piece of old wool blanket. This shoots well and doesn’t generate heavy recoil.
Shot works the same way, when you start adding 3F powder, compression wads, and nitro cards, and heaven knows what else, you can almost alway expect more recoil, and often blown patterns. Light natural wadding, that will disperse without blowing through the shot column, and greased blanket wad on top to hold the shot in is what I use.
Hungry Horse