You may recognize the gun. I have a single 20 pound lead weight that is bolted to mine that works really well. Since lead is a gummy material I had to lube the drill with 2 stroke oil so it would not bind up and break. Then placed the weight where I wanted it then transfer punched the clearance hole locations onto the sled. Then ran a tap into the lead bar and bolted it onto the sled. I have a pile of bars if you are interested in doing this and ever get down this way. I’m not sure how heavy of a cannon that you are shooting but 2 should be plenty at around 40 pounds. Btw I did not get a chance to take the gun deer hunting yet.