No matter how high quality a mechanical device is, eventually the stress of operation effects it. An AR-15 or any other firearm is no different. Modern, as well as past, firearms are arguably one of the single most well manufactured tools. They can last for generations and still continue to function. Eventually after continued use, of literally controlling explosions, parts can become loose. There is a possibility for screws and bolts to back out.
To keep your rifle functioning safely, there is a simple low cost way to catch these problems when you (hopefully) inspect your firearms before use. It involves a paint pen…
You can find a single pen Here or a variety pack Here.
Another good practice is Marking Your Magazines.
