Ahoy John ,,, the difference between 304 SS and 316 SS , is , a small amount of Molybedum (sp-?) 2% or so , is added , to reduce rust pitting of the 316 SS .
I did find on internet searches , that SS can be tested chemically , to determine if it is 304 or 316 , and that can be identified .
The test suggests to use Hydrochorlic acid drops on the SS sample ,,, as that acid reacts with the molybedum ,,, if it shows present ,,, it is 316 , if not it will most likely be 304 , which in warm water salt water environments , show rusting then pitting corrosion on your 304 SS , heaps faster than with 316 .
It is hard to find useful info on SS ,,, you have to look in many places .
I have been told that SS from China , is not always up to Mil Spec or ISO standards ,,, but that Korean SS is more reliable . The bulk of our wire comes from either place , or so I am told !
Try this website for metal testing kits :
http://sfiaust.com.au/search_results...-moly-drop-960 ,,, or this one ,,,,,
http://www.koslow.com/metal_test_kits/1542c.html
BTW we purchased our new 316 SS 1 X 19 , in Phuket , from an Aussie owned shop , that inported all his wire from Oz ,,,, the printing on the spool said Sta-Lok , and Arcos (from Oz) and now less than a year in Singapore , we have "barber pole" rust showing up on one outside strand , Drats !