Fantastic video walkthrough for an AR-15 Lower assembly

I'm old, and I've been shooting and reloading since I was about 7. I started depriming and sizing brass for my father with a RCBS rock chucker press (which I still have) have now primarily use a Dillon 1050, and several Dillon 550b(s) I have been a shooter/member of IDPA and IPSC, though I'm not current, and I have not been to a competition in quite some time. Lately I've been into shot shell reloading, and trap shooting.