Hastings Manufacturing Company since the mid-1980's has published engineering bulletins on pressure blasted cleaning media, such as glass beads, steel shot, etc., being left in engine parts, such as heads and intake manifolds, after these parts are cleaned.
One interesting thought was pointed out by one of our customers that may prove helpful in removing steel shot from the internal passages of internal engine parts.
When work Is done on heads, intake manifolds, etc., which are made from cast iron they can be magnetized either from the work being done or the fact that they may be held magnetically.
If the parts have any residual magnetism they will resist most attempts at removing steel shot from their internal passages.
A simple demagnetizing operation could prove very helpful at releasing any shot still within the parts.
Photo shows damage from steel shot.
The photo below is an enlargement of the top ring area of the piston.