I have just finished my first Ar pistol build in 9mm. Everything worked out great except that when I fire the pistol the action will chamber the next rnd but not reset the trigger. When manually racked the trigger resets as soon as the bolt clears the next rnd enough to chamber it,but not when fired. The kit came with a blade brace with buffer tube assembly. Thinking that maybe the buffer spring was too strong i swapped it out with another that wasnt as new and stiff but made no difference. Any help on eliminating this problem without having to return the upper to the dealer for who knows how long would be greatly appreciated. Thanks ET.