espnloser,
Unless you are doing extremly numerically sensitive work, for all intended purpose, a general number like 0.283 (as mentioned by arto above) will do you for C.S and 0.286 for S.S., or for most "steel".
You can google, or best to just purchase the "Mechanical Engineer's Handbook", for aluminum, glass, wood, etc to have a basic number. A change in 2 significant digit is not going to change a technical decision.
Just my 2 cents.