Good blasting sand should do the job. Good blasting sand is sized and consistent and cost only 3.28 a 50 lb bag here.
Now, I have had the same problem and I agree with 58GMCnut. One day I would blast just fine, the next day it clogged constantly. It has a LOT to do with the moisture. I know mine was not plumbed to be dry enough for blasting so I finally gave up, sold the pressurized blaster!!


1937 Chevy Pickup
In the Gallery
1952 Chevy Panel
In the Gallery
More photos
1950 Chevy Coupe
Pictures!

I'd rather walk and carry a Chevy hub cap than ride in a Ferd.
I can explain it to you, but I can't understand it for you smile