Before I get completely flamed to death let me preface this with a simple statement. This gun is not mine. An acquaintance purchased this against all recommendations from me. He is now re-considering his purchase and will most likely be buying a quality upper from a well-established company.
With that out of the way let me explain the problem. This rifle has sub 200-300 rounds through it on a static range and the ‘tactical’ rail has already started coming loose. For the life of me I cannot find any documentation on how the rail is attached to the rifle. It appears as if on the MMR ‘Hunter’ version the fore end is screwed into the barrel nut itself but it seems like its a different system on the ‘Tactical’ models. I have done due diligence and scoured Youtube, Google, emailed Mossberg, downloaded and read the .pdf users manual, visited the Mossberg owners group forums and still cannot find a solid answer as to how the rail is mounted. Even the Moderators/SMEs have no solid advice to give on that website. If there are any end users here please enlighten me. Thanks!
The pics on Mossberg’s website are pretty shitty and I can’t really tell. That said, the UTG rail that was linked above is what is on the M&P15 Tactical, at least as of a couple years ago. A friend bought one and shit started coming off that thing within the first couple hundred rounds. That said, from the pics on Mossberg’s site it does not look to be the same rail, at least not from what I can tell.
If there are no visible fasteners it’s probably screwed on with loc-tite like the hunter tube. You say it is loose. Loose how? I won’t hurt anything to put heat gun on it and see if it will unscrew.
I definitely was jumping the proverbial gun a bit on the troubleshooting. After my buddy brought his rifle in I noticed something very interesting that he failed to mention…the whole barrel is loose. I can easily move the whole barrel side to side, up+down, and even (frighteningly) slightly backwards and forwards. Going to have to properly tighten/torque the nut back on. I let him handle my DD and he is now sold on the idea of getting something a bit better. Pointed him towards the Bravo Company and he will have a new BCM upper within the month. Also convinced him to dump his barksa laser and utg scope as well.