I don't have *this* case, but I've had to cut foam to make guns fit in cases before. If the internal length is accurate (50"), it shouldn't be a problem.
I own a 20 in, Pined FSB, carry handle and a battle arms rifle length stock. I had to cut a hole in the accessory slot for the sight, and a small cut for the A2 muzzle brake. I own a A2 stock its not installed but it looks like I would only have to remove the pre cut foam where the stock would be placed,there is plenty of space.