That is the website of the Muzzle Loading Association of Great Britian. Post your question there also as they have many experts on 19th Century British arms.
On the HC program "Pawn Stars," someone brought in a 3/4 musket. It was, however, a flintlock. The arms expert explained that some officers commissioned them for their children. I like the idea that some were made so the cabin boys and powder-monkeys could have something manageable to shoot.