Chinese 84S flashhiders were not cast (You can see the line down the middle of the part). The profile is also completely wrong. I think its a reproduction of a 5.45 AIMR flashhider.
The part you are citing is a the 7.62 version which has a shorter cage. The 5.45 version is longer and is much closer to what the OP posted.
The part you are citing is a the 7.62 version which has a shorter cage. The 5.45 version is longer and is much closer to what the OP posted.