No this isn't a musical horn!

These Powderhorns were used to carry gun powder for the muskets in the Revolutionary and civil war times. (2 Civil War copper/brass ones, pictured together).

The unique design of the Revolutionary one looks very much like an old viking horn, or something you'd see being used in the Swiss Alps to summon for dinner.
But in fact these designs were used for many years. Strapped around ones neck/shoulder, they were found on any soldier with a musket needing to be fired using gun powder.

The civil war designs got a little more advanced, as they even had adjustable tops on them to measure the correct amount of powder to dispurse. Also made from Brass/Copper, they wore like a Penny.

The Revolutionary ones are VERY RARE, and very hard to come by. In most cases in conditions like this, with etched initials or modified slightly from original designs.