I'm thinking of loading some 12 bore with multiple(2 or 3) .733 round balls. I'm useing quickload to try and get an idea of load data. I"m adding the diameter of 3 roundballs and wads to get a loaded length and useable case capacity. And adding the weight of the 3 roundballs(567 grains) and wadding loaded in a brass case. It's looking like 40 gns of RL10 might give 850 fps at 21.5ksi??
This will be used in my 1887 lever 12 ga with 20" bbl(smooth bore).

Has anyone played with multiple projectiles, or any thoughts on loading? I could go with a 50 BMG case cut down to 2.5" for a thicker base and walls, but I'd loose case capacity.

Dixie slugs makes a Tri-ball load.
The balls are not that large of diameter,
but about .605" --315 gr each --They use wadcup.
Works in full choke guns. Total load not being
a huge weight they get decent speed.

Oh for dependable ignition with shotgun primers
use our powders we show on 12ga FH thread,
or us a starter powder..Ed

Yup- My 12 GaFH Quadracones are 4 250gr conical slugs each with an eccentric hole to aid dispersion. Very impressive at 1800 fps.
I also tried two brass balls and a brass ball and OOB combo. All worked just fine with my cases.
Makes a real mess out of a Honda Civic!-Rob

HA!HA! Rob, your post reminded me of a time LONG AGO!! when a young man and a bud loaded up 3" 12ga with 2 69 calibere steel ball bearings and a hefty load of blue dot, then shot the shit out of a 69 dodge wagon, killed the engine block and split the shotgun receiver down the middle

According to James Gates, maker of Dixie Tri-balls.
If you are going to cast these out of lead then cast them as hard as you can. There are problems if the lead is soft.
You can go to Cast Boolits forum for more details.

Cheers, John