It isnt a through bolt. It is a wood screw with a straight shank that interference fits with the hole in the wood. The wood screw has machine screw threads down the hollow inside, that receive a screw from the action side, holding the action into the wood. Most of the guns have an elegant, rounded wood to metal fit in that area, that complicates the fitting. The hole was drilled AFTER the stock was rough turned, at the factory. I was there.
If it was easy, it wouldnt be a problem getting a stock made for a Darne.
But, it is a problem. Yes, it can be done. But, there are few volunteers, here, or, in France.
Here is a live one, a guy looking for the work. You do wood work, SKB, right?

Best,
Ted