IC13 Arms and Accessories has a locking chamber flag for AR-15 and Remington 870 shotguns on display at the Great American Outdoor Show.
The IC-Lock plugs into the ejection port and is locked in place with a key. It is metal construction. According to IC13, an added benefit to the IC-Lock is that it prevents the AR-15 from being disassembled. I am curious how that works. Couldn’t you just pop both take down pins and slide the upper forwards to disassemble it? Similar to the PDW style stocks that use the NEA style bolt, where the bolt and spring sit in between the upper receiver and buffer tube. You cannot hinge the upper like normal. You have to pop both pins and then the upper can slide forward and up off the lower receiver.
IC13 has the “Remove in case of jihad” or their standard IC13 logo engraved on the IC-Lock.
Below is the IC13 870 lock.
The IC-Lock retails for $29.95 for either the 870 or AR15 version. You can check them out on their website.