better Ryobi Caulking Gun Plunger

The stock plunger did not press evenly on the cartridge plunger leading to enormous leakage at the back of the cartridge. 

I almost exclusively use the polymere cartridges from Würth (German professional hardware store)

I used a metal washer inside of the part to distribute the load of the push road. Add a pause in the gcode to insert said washer. The cavity is 30x1.6mm big.

Use plenty of infill and shells.