Receiver with integral hinge for folding buffer extension and butt stock assembly

A firearm lower receiver configured to mate with an AR-pattern, auto-loading upper receiver assembly, comprising:

• a lower receiver body;
• and
• a hinge mechanism having a fixed part integral to the lower receiver body and having a moving part to which a buffer tube is mounted, the hinge movable between an extended, operating position where the buffer tube is substantially aligned with the bolt carrier and a folded position;
• the fixed part including a carrier blocking member movable between a blocking position where the blocking member prevents rearward movement of a bolt carrier in the upper receiver and a displaced position where the blocking member does not interfere with movement of the bolt carrier, the blocking member being spring biased toward the blocking position;
• a striker extending from the moving part and configured to contact the carrier blocking member and move it against the spring bias to the displaced position when the hinge mechanism is in the extended, operating position.