10, 11 or musket, is all fine here in washington. Any cap that fits onto the nipple makes the gun legal. But It still has to be exposed to the elements. I do not know that gun and I agree that it does not look to be legal. There might be a kit for it but I am not sure. I would look at the cva elkhorn. Its my go to gun right now. It is not a whole bunch more money and it is legal here.