Hello all,  I recently put together an ar 15 pistol (registered pistol reciever + 7.5 upper) when I took it out to test things out  I encountered problems.   I cannot get past 2 rounds, I have tried different (synthetic, steel, and aluminium) mags, both partial and fully loaded.  10 out of 10 trys yeilded one empty casing above the bolt and one fresh round pointing above the chamber and not going into battery.  
This occurs every time without failure.   Any insite on this situation would be appreciated.  Thank you in advanced.

sounds like a possible short stroking issue.  

Here's a cut'n'paste from the troubleshooting sticky:

"-Load the rifle with one round from the magazine. Use quality ammunition and a proven magazine for this.
-Aim downrange and fire, the bolt should catch on the bolt stop. Hold the rifle as loose as possible.
-Reload and repeat the process if the rifle does not lock open Depress the bottom of the bolt stop before firing this time. This allows for weak magazine springs, sticky followers, or an overly strong bolt catch spring.
-If the bolt does not lock open then there is a gas system problem. Investigate and repair the problem.
-If it only locks open with the bolt stop depressed, repeat the process with a different magazine. If the rifle still fails to function then look at the bolt stop as a probable culprit."

Thank you guys turns out it was a weak extractor spring used a wolf  extra power and bang bang it works!