A bit late finding this thread, but I will reply in the event others find it in the search as I did...
I have two of the Turkish AR "looking" shotguns. I have a Panzer (gen 3) and an MKA 1919 Match. I have a lot to say about these shotguns, but I will refrain unless someone request the book I can type on what I have done with and to mine. I have tested more than a dozen different loadings in my auto-loading shotguns for function.
The Panzer Gen 3 AR-Twelve is the most versatile in that it is inherently more reliable with a wider range of loadings. I am a tinkerer, and did a Bench Break-in on it as a machinist would do. Having force do all your break-in in an aluminum receiver firearm I think is just unwise, but that is my opinion and is based on my knowledge and experiences. That said, mine will run 1200 fps Estate white-box bird-shot reliably. This is not common in auto-loaders. It has an auto-adjusting gas system, no settings or any parts to change. (basically a progressive vent system) I have run some fairly heavy magnum loadings in it also, but not by the hundred, unlike S&B Buckshot, its primary use.
The MKA 1919 has two changeable gas rings for "heavy" or "light" loadings. Takes a bit of effort to change these out. This gun has also been worked by myself, so out of the box function, I can't really comment too much on. It won't run anything int he 1200 fps range unless over 1 ounce, but loves the S&B Buckshot (the cheap stuff, not Perfecta) and Winchester Silver box steel bird-shot, which is all plinking cheap.
I chose these two because they share magazines, have very readily available steel magazines and accept drums. These are test guns for me and have seen thousands of shells each with no parts failures.
Panzer AR-Twelve
MKA 1919
Keep in mind that neither of these is much more than the feel of an AR type rifle... they do not function anything like an AR. These do not share triggers or really any other parts with AR type rifles. No buffer tubes etc. They are also large, as you can see from the image of the MKA 1919.
With all of this said, I have enjoyed mine a great deal. Out of the box can be hit any miss with these guns from what I read for years before I bought these two. It seems the current gen Panzers addressed issues of the earlier models. The MKA have always been relatively reliable, but with a little higher requirement for ammo quality/pressure.
If you have any questions about these two shotguns, I will do my best to answer. While I am not an "AR guy" or a "auto-loader shotgun guy", I do know these particular guns well as I have been through them and done 922r compliance work with them. A quick look on the internet shows these are not just "everywhere" as they were in last couple of years.
Stopping here...
MrBlackCat