Yes. I put a rubber stopper in the muzzle and one in the breach. I then cover the breach face with a special little plug but you could use just about anything to keep the blast media away from the breach face.
I use a foam earplug in the muzzle and clay to cover the chamber and breech face. I use a q-tip to lightly oil the breech face before adding the clay to aid the removal. I do this before I blast and leave in place until coated.
Lauer Weaponry sells a great urethane plug kit. It's cheap and comes with a bunch of urethane plugs of all different sizes. I use them to plug everything from muzzles to the tiny scope base screw holes on top of actions.