Multiple balls is not a bad idea and is one that should be tested.

Years ago, I purchased a Marlin .444 due to an article in Gun Digest on the Marlin .444 being one of the best survival guns. I never got around to trying shot loads in it, but did use shot loads in .444 brass in my .410 shotgun with excellent results, as good as comercial 2 1/2" shot shells.(which are better than 3")

The 'best' loads were with 3 .451" balls, sized down (lube sizer) to .430". These were loaded in triple ball loads, and would stay in about 13" at 100 yards, 3 or 4" 'patterns' at 50 yards.

Double or triple ball loads might be interesting in that .45/410 reveolver. Seems to me the shot load required 12gr. Unique was the load in a .444 or .410 hull. Pressure was not a problem at all with velocity in the 1,600 or 1,700fps range from the rifle. This gave virtually identical ballistic results to a .45 muzzleloader, except for the multiple balls making virtually instantaneous impact for even better results on 'game'. They were the 'assault' load for the .444. - 6 rounds of 3 balls each = 18 projectiles in a very short period of time delivered on target.