ASH230 refers to SAE AMS spec AMS 2431 /2 Cast Steel Shot, High Hardness (55-62 HRc)
AWCH28 refers to SAE AMS 2431 /8 Conditioned Cut Wire High Hardness (55-62 HRc)
MI 230H refers to cast steel shot media made especially for Metal Improvement Company (thus the MI in the title, H means high hardness. They also use R for regular hardness)
S230 refers to size of shot as listed in SAE J444. Note: this only gives size, it does not give chemistry or hardness information.
These sizes are essentially equivalent to each other so you can choose whichever you like. You will have to experiment to determine what air pressure is needed to achieve the compression at 10 micro. This will then be converted to Almen intensity which you can use to control the consistency of your process.
