Responding to your request.
Pre-1900s artillery projectiles are my specialty area of relic-study.
Sorry to have to say, but for several reasons I am 100% certain the object is not a Bar-Shot The main reasons are, its form is quite different from the known varieties of actual Bar-Shot. (Do a websearch for images of Bar-Shot in museums, not at antiques/Militaria SELLERS (especially not Ebay, which is full of fakes.)
1- Its total length are much longer than any actual Bar-Shot I've ever seen.
2- The bar on actual Bar-Shot is square-bodied, but this object's bar is cylindrical.
3- The "extra" hole in each of the two balls has no purpose on an actual Bar-Shot. The holes have some sort of purpose in the object's actual function (which isn't artillery).