New to the forum too. I just cleaned my virgin MP 15 Sport out of the box. Watched a three part video for some basic tips. Here is part 1

Cleaning the AR-15 (1/3) - YouTube

One area of variation, however was the extractor portion of the bolt. Held in by a small pin, the video talked about a small spring that could be misplaced when the extractor pin was removed and the extractor lifted off the bolt. I found no such part to the extractor so I assume that the AR15 shown in the video was a different model. BTW, if somebody in this forum would tell me I lost the spring and should get down on my hands and knees and start looking, I would appreciate it.

The rest of the series (3 or 3 on youtube) seemed thorough and was a little more easy to watch with good use of closeups. It was hard to see what the NSSF guy in the video link above, dressed in a black shirt, behind the black metal of the MP 15, was talking about.

Looking forward to my first trip to the range this week. Happy Shooting.