If you want to turn your AR pistol into a rifle, all you need to do is add a 16 barreled upper and a stock. Just make sure that if you return it to pistol configuration that you detach the stock first and an forward vertical grips you may have attached to the weapon...f the firearm was already classed as a pistol with a barrel shorter than 16 inches, it cannot be converted to a short barrel rifle and legally registered. An AR15 pistol can be rebuilt as a legal length 16 barrel rifle at a later date, but not as a legal short barrel rifle of less than 16 inches.
Step 4. Add one or two handfuls of garden soil or finished compost to the tumbler (see References 3). Garden soil or finished compost adds beneficial bacteria that helps start the decomposition process.
Place the rocks to be polished in the barrel of the tumbler. Use the abrasive grit first, then the fine grit followed by the pre-polish grit. Adding the rock polish is the last step. Run the tumbler for the required amount of time with each step as stated in the tumbler instructions.