Good day, I have weighted a few stocks to tame recoil. And depending on the stock there are a few ways to do it.
In a solid wood stock I prefer drilling a hole into the wood around 3/4 inch, and maybe 4-6 inches long/deep, and putting in a steel rod, with a price of rubber ahead and behind it. This will add around a half lb. You could add more by using a denser metal like tungsten and get that to a lb and a half.
I would not encourage lead shot, as it oxidizes over time and can get messy. If you are going to go that way, put it in balloons and tie them off to keep it neat.
A softer recoil pad can also help a lot, as well as the reduced loads listed above. If you reload this can be easy to accomplish.
But given the option, the drill and rod insert works best. And if the rod does not weigh enough you can always then install a mercury reducer in the drill hole.