One thing to consider with a sub-gauge gun and light loads, is that the thing that makes them less lethal than a heavy 10 gauge load is pellet count. A smaller pellet count leaves you with less pattern density, hence less lethal range. So, if you take a light load, and use large shot like lead #4s, the limiting factor, pattern density, is more of a problem than it will be with say lead #6 shot, or even lead #7-1/2s. And there will be a wide range gap between pellet energy and pattern density. It's a give and take. Might as well try to match the pellet energy with pattern viability to maximize the gun's effectiveness.