Get yourself a smooth bore if you want decent patterns. I have a shotgun barrel for my TC new englander that I used to duck hunt with quite successfully. Non toxic being a requirement I had to do some experimenting with steel shot before finding a combo that patterned well. I ended up with 110gr of prodex with a modern steel 12 ga wad over the powder and 1 1/8 or 1 1/4 oz of # 2 steel shot with a felt over wad. It worked great.