BS. I’ve been shooting since I was 10 years old, I am now 68. I was considered an expert by many, and am still considered so by my friends who are still alive. Criticizing people on nit picky things such as .45 auto VS .45 ACP is just plain stupid, period.
For precision, the term 45 ACP is the best for communication in training. I agree; for clarity everyone knows what 45 ACP is.
Let me know how stupid it is when your student goes to Walmart and asks the kid behind the counter for ammunition that isn’t listed on the boxes.
Your goal is to teach the student and not brag how much you know.
Help the student understand and forget the ego.