316L is a common steel grade for lower cost body jewelry made in Asia and would not be considered acceptable for use in initial piercing by APP standards. 316L steel is a material more commonly referred to as “surgical steel” which is actually in reference to surgical tools, and not implants or items meant to be worn under the skin.
Association of Professional Piercers jewelry standards would require steel used for initial piercing to be ASTM F-138 implant certified. Meaning it is tested and certified as being safe to wear under the skin.
I’m not trying to be contrary, but when I have looked into medical implants (I have early onset arthritis in my knees), they encouraged me to look into 316L Stainless Steel and Titanium.
"Type 316L stainless steel is popular for surgical practices as it is the most corrosion resistant when in direct contact with biological fluid. […] This type of stainless steel is particularly effective as a surgical implant when in cold-worked condition. What makes the Type 316L ideal as an implant device is the lack of inclusion in this material." - http://www.azom.com/article.aspx?ArticleID=7156
From what I can tell, the real debate among piercers seems to be between 316L (low carbon stainless steel) and 316LVM (low carbon vacuum melted stainless steel)?, the materials they mentioned to you are general designations so that you could learn more as a lay person. The specifications for steel, Ti or other materials for human implant are highly regulated starting with ISO and ASTM standards which are like recipes that include testing requirements for safety. Read more herehttp://brnskll.com/shares/safe-steel/