There is NO loading of .410, not bird,buck, or slug, that makes an acceptable HD weapon due to sadly lacking penetration - it may wound, but will NOT stop.
The .410 3" buckshot load of five 000 buck has the same muzzle velocity as the 12ga load of eight 000 buchshot. How does a .36 lead ball at the same velocity have less penetration just because its coming from a .410 instead of a 12ga?
Why have a .410?
My M6 Scout is 18 inches long folded and can go with me when a longer shotgun is just not convenient.