What you have is a set of back action locks most likely from a double barrel shotgun, or possibly a double rifle. If I had those parts I would be really tempted to build a gun with them, stocks and modern barrels can be bought for reasonable prices and it would be a fun project. ( I really like building black powder guns) As to their origin, they could be European, or American, it's hard to tell on a lot of them unless they are marked. Check the locks for any kind of proof marks, also the large part in the second pic, (the "tang" which held the barrels into the stock) is a good place to look for marks.