I know the discussion is about M38A1 but another vehicle of the same vintage, my M135, had many self-locking nuts of the type shown below, BUT the wheel nuts were ordinary commercial items (no locking function). I don't recall ever having seen self locking wheel nuts. Maybe I'm not observant enough... Also some of the distorted lock nuts require significantly more torque to run down the bolt/stud compared to a regular nut (and more as they get larger).
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