Please do us all a favor. Take out the ramrod and drop it down the barrel. If it goes all the way down and make a"Ping!" when it hits bottom, it means the rifle is not loaded. If it goes "Thud!" and the ramrod does not go all the way down, it means there is a load in the barrel (in frontier times, it was common for a rifle to be stored loaded over the fireplace where all you had to do was cap the nipple and you were ready to shoot in an emergency), and you should locate a gunsmith with the equipment to blow the load out using air pressure.
We'd feel better knowing that firearm is safe. Some of the Band of Fellers, myself included, have stories about finding flintlocks and caplocks in antique shops or estate sales that were still loaded. I have read stories about kids playing with muzzleloaders who have accidentally shot their playmates by screwing around with matches on the nipples or the pan.
In terms of maker, I can't help you. But the type is generally known as a Hawken rifle (after the original gunsmiths who designed and built them, always by hand), a mountain rifle, or a plains rifle. They are an evolution of the famous Pennsylvania Rifle, being shorter, with a heavier barrel, and of larger caliber, able to handle any wild animal on the way West.
