while the lower receiver and stock use high quality

For М4 / М16 / МР-5 / SCAR

you need to put together the stock and the upper of the A2

BUFFER TUBE

the barrel cannot exceed 12 mm from the foremost end of the thread

Prometheus Nozzle M16A2・M4・RIS・SR-16・M733・S-SYSTEM MB BE WHISPER while the lower receiver andPrometheus Nozzle M16A2M4RISSR 16M733S SYSTEM Built in O ring for a superior air sealPOM Resin build The Prometheus air seal nozzle is a simple yet effective upgrade to your compression unit. The unique built in o ring enhances your air seal while being the perfect length for your chosen platform. Excellent feeding, loading, and firing of BBs allows you to optimize your air volume and air seal, for that perfect shot each and every time. The POM resin