Sentinel gun cabinets are produced by Stack-On. This safe-manufacturing company markets the Sentinel brand of cabinets as an affordable alternative to a gun safe. Sentinel cabinets are lighter than most safes, and they do not have the same level of security that a traditional safe does. However, these cabinets do contain a coded key lock that is difficult for criminals to break. The rounded key to a Sentinel cabinet turns a bolt that locks two metal posts at the top and bottom of the cabinet. You must have the original manufacturer's key for the lock to operate properly.
Locate the keyhole on the front of the cabinet. The hole is round and has a small vertical slot at the base of the hole.
Insert into the hole the original Sentinel key that came with the cabinet by aligning the small post on the bottom of the key with the vertical slot in the keyhole.
Turn the key counterclockwise 180 degrees until the key stops. You will hear a clicking noise inside the cabinet as the two locking posts retract.
Gently pull open the door to access the cabinet's contents.