I shot some Korean M2, I think it was KA74 in my 1903 springfield (bad gas venting design) and when I was done I had little shiny specks all over the lens of my glasses. 15 years prior to that I shot it with some ancient primers I had found, they were gold colored CCI's and one primer pierced and shot gas in my naked eye. Fortunately it didn't require treatment, just hurt! I haven't been without glasses since, although sometimes while shooting in the heat I'll get frustrated with them fogging up and being sweaty and yank them off.
Also if you shoot steel, fragments can come back!
Phillip McGregor (OFC)
"I am neither a fire arms nor a ballistics expert, but I was a combat infantry officer in the Great War, and I absolutely know that the bullet from an infantry rifle has to be able to shoot through things." General Douglas MacArthur