Roger that, zippy.
After experiencing the difference in my neighbors gun, I added some weight to a 12 gauge, Remington 1100 with a synthetic stock.
The lighter weight of the mostly empty stock, made the gun kind of nose heavy, anyway.
At first I added enough lead strips, just in front of the recoil pad, to balance the gun about the same as one with a wooden stock.
Not much, maybe a few ounces, but even that little bit, in addition to improving the balance, did have some effect on recoil.
Well, if a little bit works, why not a whole lot more.
Ok, so then I just about filled the stock with another pound and a quarter of lead.
Boy, what a difference in recoil, even with regular target and game loads.
Very nice.
And the balance isn't too bad, really, with its 28" long barrel, especially when the mag is full.
But I'm definitely going to make up some lead filled rounds, as you suggested and play with it some more.
Messing around with guns is fun.