Just a question concerning sandblasting of the action. I intend on parkerizing a barreled action. I plan to plug the muzzle and the chamber end. However, I'm concerned about the lug recesses. I don't want to screw up these surfaces. Any help is appreciated.
Thanks,
Regards,

Just clean everything thoroughly when you are finished. Unless you stick the nozzle of the gun in there you won't hurt anything. You can wad up a piece of paper towel and shove it in there but I think you are better off just putting more thought into your movements when you are doing the sandblasting.

I don't think you ought to sand blast. If anything, use aluminum oxide of the appropriate grit size.

You might want to consider Bead Blasting as an alternative!

I read somewhere recently that you should use glass bead media when blasting the surface of an action & barrel. The glass bead actually peens and work hardens the surface where sand cuts or abrades the surface making it more prone to rust and surface pitting.

Use beads. And I would tape off the action so you are not blasting the rails, feed ramp, etc.