About 5 years ago I did moderate amount of pattern testing bismuth (Bi-Sn alloy shot) in 12 and 16 gauge doubles with nominal full and 1/2 chokes (based on measured constriction) and 75 cm barrels. These were either "upland" loads or handloads -- muzzle velocities in the 1200-1250 fps range -- and shot charges from 24 to 36 grams, usually 28-30 grams (1,0 to 1 1/16 oz). Got really tight, even patterns, with 1/2 choked barrels giving over 70% at 40 yards and full choke barrels giving about 80%. Shot sizes were #6 and #3 (labled #4) I found very few holes on paper that were from fragmented pellets. One load was factory buffered #5 shot, but was not patterened on paper. The 24 gram loads were 16 ga scatter loads of #6 shot, using PolyWad SpreadR disks, for decoying ducks (about 30% patterns at 40 yards - about 100% at about 20 yards).
Used that supply of Bi-Sn ever since for decoyed and jump shooting ducks and occasional goose. Performance (penetration) was very similar to that of hard Pb-Sb alloy shot, especially Cu-plated shot (both giving little dragging of feathers into flesh). Size #3 pellets usually completely penetrated mallards at 30-35 yards. Very few pellet fragments found in birds. Size #5 buffered loads were used on canada geese with clean kills at under 40 yards, ditto for #3 shot.
Understand that alloying with Sn (tin) reduces brittleness. Also understand that this was either not done initially or that amount of Sn not optimal.
Totally satisfied with bismuth for my duck shooting. Also used some #5 Kent TM Upland loads (1250 fps). Also killed well. Maybe TM is better for pass shooting beyond 40 yards, I have no experience with this.
Niklas
