An issue impacting a very small number of Crosman DPMS SBR Full-Auto BB Air Rifles is that the green seal is installed backwards at the factory. At first the gun will appear to work normally but once the CO2 pressure drops it will no longer operate (usually after the first magazine is expended).
The good news is that this is a very easy fix you can do at home, and to help we have provided this quick tutorial video.
If you are still having trouble after watching this, or do not feel comfortable doing it yourself please get in touch with us by going to the following page: https://www.pyramydair.com/contact-us
Link to the Crosman DPMS SBR Full-Auto BB Air Rifle: https://www.pyramydair.com/s/m/Crosman_DPMS_SBR_Full_Auto_BB_Air_Rifle/4571