Garands did not have alot of problems those in the Pacific,Normandy,the cold of theArden (father was tech sgt at bothand unit got a PUC) or Korea. Like you state any auto system can pose a problem but under combat M-16 's are awful compare to most anything else except that lovely squad weapon the French gave us to use in ww1 lol.
Poor performance ? Ask anyone about stopping power from the M-4 variants past 75 yards or nam vets in the thick stuff. Terminal performance dropped so badly in the M-4 they had to go to a different bullet and even that performance is only good at shorter range.