Acepro asked me to take a look at this object. I am complying with his request.
Unfortunately, it seems to not be a Bar-Shot... for three reasons:
1- (Most important.) In the photo showing its entire body, the "ball" on its left APPEARS to be egg-shaped, Actual Bar-Shot balls were round, like cannonballs, or half-balls (see photo below).
2- On ALL of the "documented" actual Bar-Shot that had the balls connected by a single bar, the bar is square-bodied, not round-bodied (again, see photo below).
3- On actual Bar-Shot, as shown in the photo below, the bar is much longer. Notice that the bar on your object is only a little bit wider than a man's hand-width. In view of that and reasons #1 and 2 above, I have to believe this object is a weightlifting Dumbbell.
I should mention, on nearly all of the actual Bar-Shots, only half-balls were used. That is because two whole balls would be twice the weight which the cannon was constructed to be able to shoot safely. "Overloading" the cannon by firing double the normal weight of projectile could cause the cannon to burst. That is why half-balls were used on Bar-Shot.
But for the moment, let's set all that aside, and rely on the usual tests for determining whether or not an object is an artillery projectile.
1- Weight the object on a precision weighing-scale, such as a Postal Shipping scale.
2- Use a caliper or a Pi-Tape (also called a Diameter-Tape) to precisely measure the diameter of the balls. If they are not the exactly-correct diameter to properly fit any of the calibers of smoothbore cannons, the object is not an artillery projectile.
If you are willing to do those precise measurements, please let us know the result.
