On further checking, I found that Mike is correct and that carbide penetraors were post-WWII. My error, and apologies.
Mike, I have been reading an article in Firearms News which is essentially a rehash of all the old garbage about the "perfect" Johnson 1940 rifle ("the most reliable self-loading rifle ever made") and the M1, repeatedly denounced and condemned by the author, Jim Dickson. FWIW, I once owned two Johnsons, both brand new when I got them, and fired both with M1 Ball, M2 Ball and AP. They were good guns, but not the miracle weapons the writer describes. If you have read the article, I would like to see your thoughts and comments.
Jim