I would like to install a balancer for a suspended rivet gun above a worktable. Should I put the balancer on a rail or on a pivot to move it around? Anyone got experience with that?

This is a balancer https://airpress.de/balancer-8-10-kg-2-5-m-49187
This is a rivet gun https://www.mitre10.co.nz/shop/makita-rivet-gun-skin-18-volt-2-4-to-4-8mm/p/350765