The term "square load" is some what misleading. The most significant factor is the shot column height. A one oz load would be "square" in a 16 gauge but a load with the same column height would not be "square" in any other gauge.

The second most important factor is the ratio of column wall area to volume. The shot next to the wall will suffer more deformation than the shot next in the center. It's this effect that modern plastic wads do the most to alleviate.

In practice, 1-1/8 oz in a 16, 1-1/4 ox in a 12, or 3/4 ox in a 28 will pattern well. The 20 and the 410 are overloaded. Especially the 410. I've always wondered why the 410 enjoys the popularity it does when anything the 410 will do the 28 does better. At least for the 20, proper loads are available, you don't have to overload it.

What hurts the 16 is the propensity for manufactures to build them on 12 gauge frames so they loose their potential weight advantage over the 12. If you have to lug a 12 gauge it might just as well have a 12 gauge hole through it.

Last edited by unspellable; 01/03/07 03:20 PM.