What do you really want to know about AR lowers?
If your questioning how to build them, look on GOOGLE, as there are excellent videos on how to build them.
All my AR's i built myself.
I have a friend that builds all of his so he will be helping me get mine together. I'm not worried about the easy stuff like changing handguards or mounting the upper. I just do not want to screw up my lower parts kit or bolt carrier so he will be lending a hand. My goal is to have this gun finished in three weeks. Next week I'm going to buy the handguard, trigger guard, grip and butt. Then the next week I'll buy the upper and bolt carrier.