[alanint]

Taking this one step further, I build complete dummy rounds.
Pull the bullet on a live round, remove powder, safely fire and remove the primer, follow Vlim's advice and place a pencil eraser or silicone from a tube in the primer pocket, fill cartridge case with sand or other neutral media, epoxy the bullet back into the case.
Voila! a dummy round.

I have built these in various calibers. My son learned to load a Garand this way safely. I also give them a pass with red spray paint to quickly distinguish these from live rounds.