I do not know if AR-15 is trademarked by anyone, but I notice other AR makers avoid using it.
M4 is not a registered trademark, we don't need to resort to M4gery.
AR-10 is trademarked by Armamlite
M1A by Springfield
Model 700 by Remington
Model 70 by Ruger
..and so on. Companies are very protective of their trademarks. Allowing them to become common usage can cost them millions of dollars. Many laymen wonder why others get particular about the meaning of words. It's because those who know about such things, like lawyers, engineers, technicians, PR people, writers, photographers, programmers politicians and so on, make their living by words and what they mean. Professionals are judged and critically so by the language they use. If that professional does not know the difference between a clip and a magazine, it says there is a gap in their knowledge on the subject. If I use language for aviator and hospital oxygen interchangeably, the Director of Maintenance will be rightfully concerned I may not have the required knowledge and experience to work on aircraft for an air ambulance service.
The correct meaning of words can mean a life. Just because you do not know what you do not know about the importance of the correct use of words, it doesn't mean that it is unimportant or just somebody getting their knickers in a knot