Hello everyone, I am new to the AR15 platform. I have been looking around the web for answers to my questions, but I have yet to find anything useful, so I figured I'd post on here. I am wanting to more deeply understand how the internal components of the lower receiver of an ar-15 works. Here are some questions you guys can hopefully help me with:

1. What position is the hammer in after firing the last shot and the bcg is locked to the rear? What I mean is, is the hammer retained by the disconnector, by the actual trigger at the sear, or does it fall forward freely? This is assuming if you let go of the trigger, as per usual when firing the last round in a mag.

1.5. What if you empty a mag and don't let go of the trigger, in what position would the hammer be in?

2. If the disconnector is retaining the hammer, is the firearm still considered "cocked". Or does the hammer need to be held in place at the sear (by the trigger) for the firearm to be considered cocked?

3. If the trigger is released while the bolt is locked back, what is preventing the hammer from falling forward?

4. Can the hammer engage the sear if the BCG is locked in the rearward position?

5. What happens if you pull the trigger when the BCG is locked rearward?

Thank you to everyone that can give their input on this. I am a bit OCD when it comes to things like this, so please don't roast me for my dumb questions.

https://www.youtube.com/watch?v=wAqE-KLbiYc

Still doesn’t answer my questions.

Alright, this helps a lot. Two more things:

If the bolt is locked in the rearward position and you pull the trigger, you’re saying the hammer won’t come in contact with anything right? Because it sure seems like the disconnector would engage the hammer if you pulled the trigger.

Also, if the bolt is locked in the rearward position, which means the hammer is far, far back, should you still be able to engage the safety?

Do yourself a big favor and get one of these. It will answer all your questions as well as the ones you haven't thought of yet.
As to your question, with the bolt locked back it is riding on top of the hammer and pulling the trigger it won't let the hammer move so....
And yes, you can still engage the safety with the bolt locked back.

D_man hmmm. That makes sense,except when the hammer is cocked and I pull back on the charging handle to lock the bolt (either w an empty mag or with the bolt catch) I cannot change the selector from fire to SAFE w a simple flick. It feels very binding and if I force it only then does it move to safe. I took the upper off and I inspected the lower and this was what I found:

When depressing the hammer w my thumb (to simulate bcg being pulled back and over the hammer), the switch gives little resistance when going from SAFE to fire. In fact, it even gives me cleareance to depress the hammer even slightly more down.

When depressing the hammer w my thumb and switching from fire to SAFE, the selector binds up at about halfway unless I ease my thumb off the hammer slightly to give some sort of clearance for the switch to move completely to SAFE. It feels like the bcg is not giving enough clearance to the hammer to more forward a little bit so that the selector switch can move freely to SAFE.

This is a lwrc m6ic direct impingement rifle that is pretty much brand new and stock; I haven’t made any real changes to it besides iron sights and a sling. What could be the problem? Is this normal?

I’ll definitely look into getting one of those mechanisms!