I've used 58 caliber wheel weight round balls in a Stevens 20 gauge double with minute of bear accuracy. Never shot a bear but I felt better having a couple of them in my pocket. What impressed me was the vastly increased penetration compared to factory slugs. I don't remember the load but it was Blue Dot extrapolated from the Lyman manual. The right barrel shot fairly close to point of aim but the left barrel shot somewhere else. Like the old refrain about the Brown Bess, "One went high, one went low. Where the Hell did the other one go?"

JS

J.S. -  THANKS, I'd overlooked my 58 cal molds!  (not having anything in 58 cal I've just put them in the pile of moulds I've never used.)  If they measure right or right when patched it should work (fully rifled tube).  Thanks also for the bluedot note.  I reload for 10ga and the only powder that works for the loads I use is bluedot.

This was one of the rare times that I didn't keep notes on what I was doing. I sure do wish I had now! I think I used a shot cup to get it to fit and cornmeal for a filler. Wish I could be more help.

JS

Yes, standard factory (H&R) 3" chamber.  Oh yea, I guess it would be good for me to do a chamber cast and look at the throat.

Slugs are casting at about 350gr.  Casting at about 740 to get slugs to fill out - and as expected weight varies a few grains either way depending on the temperature of the alloy.

Alloy is WW + tin  (8% tin 2% antimony).  (if I were hunting with this it would be lead and a whisp of tin.)