Many Civil War battlefields have those monuments of three smaller balls supporting a larger one. Some folks think they're cannon balls, but it's really a buck and ball arrangement.
In his monograph on the ammo used at Gettysburg, Dean S Thomas documents B&B use by many units in the both Confederate and Union Armies.
In the present, I regard Tri Ball as not any improvement on good old 00 and has some downside. A .69 Caliber round ball can penetrate much farther than .33 pellets and thus increase the chance of collateral damage.
However, YMMV. Do test and evalute thoroughly before use.....