I was forced into the situation I described because I wanted an O/U with a straight hand stock.
I was an idiot, and listened to some moron, perhaps he was only an imbecile as I think about it, who said you can cut a pistol grip stock and end up with a satisfactorily balanced straight hand shotgun.
You can't. The buttstock has too much material removed to balance the shotgun when first stocked.
Cutting 8-9oz of walnut from a pistol grip stock shoves the balance about 4 inches past the hinge pin.
My efforts were to repair my ignorant mistake.
