For what it is worth - I, too, found myself with some Herco and not a lot of use for it. I used to use it for 28 ga loads but recently changed to Pro Reach for my 28 ga reloads. I have some reclaimed shot and measured the weight of the drops of reclaimed shot from a bushing that is supposed to drop 1 1/8 ounces of regular shot. I found that the result was a weight of very slightly over one ounce (ten measured drops all weighed between 450 and 454 grains - one ounce is 437.5 grains so I was between 2% and 4% over one ounce.)
I used the Alliant formula for 1 and 1/8 ounce of shot and 25 grains of Herco powder. I've used both a Red PC and a CB 1118 wad. The volume of shot fills the wad nicely in spite of being lighter that what is called for. The result is that these shells burn dirty but they do an adequate job on targets to 35 yards at sporting clays. I suspect that if I had some Federal 209A primers they would burn a bit cleaner but I don't know that for a fact.
Again - for what it is worth. JPM