You don't have much to worry about, in any event. A Darne doesn't really care if it has 2 3/4" ammunition in it's short chamber, and that gun was triple proofed.

You might look into having a pitch adjustment made on that stock, maybe with a recoil pad thrown in. A Darne stock is a poor cantidate for bending, since it has a wrist with a steel rod down the center.

Good Luck.
Best,
Ted