It's a low quality Belgian gun given a "Name Brand" to fool the unknowing; Sam Holt, T. Barker & W. Richards are other examples. It can not be made safe to shoot, with ANY load.
More here
http://www.picturetrail.com/sfx/album/view/20091267
BD is possibly the mark of
Bauduin Doyen, a Nessonvaux damascus barrel and gun maker.
AL was used by
Arnold Lochet, but he was a post-1900 maker.