No, it will probably be fine. You're going to want the grain to travel through the wrist anyway, so you may end up canting your pattern on the board anyway. Even if you didn't, I'd think you might still be able to make certain schools of guns with a 9" board. Figure a 5" buttplate and 3" of drop or so, plus a bit of loss from cutting. It's not ideal but it might work. As I said before though, tilt your pattern and you should be able to make any school of 18th century gun on that board.