Laugh if you want, but I have two: an A. Hollis hammer gun from the 1880s (2-7/8 inch chambers) and a Darne that probably dates from sometime prior to 1900 (also 2-7/8 inch). I use RST non-toxic loads in both. The Hollis weighs about 8-1/4 pounds and the Darne is a svelt 7-1/4. A completely different experience than the heavyweights with Roman candle loads.
