Dear MB,
First we should recognize two aspects of your request: 1) the authority to change the process and 2) the technical equivalence of changing the process.
If you are performing the peening under contract (purchase order etc) that requires the 0.093" shot size then you would want to get permission to change. If you are the part or process owner than you should proceed with your process variation review.
Technically, achieving the same intensity (probably lower air pressure or slower wheel speed, will provide the same depth of compression. However, you must be sure that the shot diameter is smaller than the fillet radius. Generally the diameter must be equal or less than half of the fillet radius.
