Anyone have experience with this stock that holds a magazine under your cheek inside the stock? Since I'm stuck for now in Jersey with a pinned stock, with the 15 round restrictions to boot, I thought this would be a good idea to use on my M&P 15. But it seems the one I got wiggles on the buffer tube. The ads say it fits commercial and mil-spec, do I understand ours is mil-spec? That's what I read somewhere. Flat back as opposed to slanted is the easiest way to tell it would seem, the diameter of the tube is something I'd have to scrounge around to find my old caliper, haven't seen it in 4 or 5 months. I KNOW it's around somewhere,,,,,,,,,,,,

Do I have a bad buffer tube? An out of spec Fab Defense piece? A knockoff? Expiring minds want to know.
I just know I can get good answers here.

If it fits both commercial and mil-spec extensions, it is going to wiggle on the mil-spec on, as the commercial one is bigger.

Won't affect accuracy, may just be annoying. You can put a couple of pieces of duct tape on the top of your receiver extension (aka buffer tube) to fill in the gap and reduce wiggle. The soft side of a piece of velcro works for this too... Many of us do this with the standard stock if the wiggle is too annoying.

I hesitate to use the word brilliant, but that may be the appropriate description of your velcro solution. Clever is for sure a word that fits, thank you!! The "wiggle" is definitely a distraction, and well worth trying to eliminate. S&W's basic stock is snug as a bug.

It (the new one) is supposed to have little grippers on the sides to snug it up on the buffer tube, but I think that they miss the mark.

Small side note, I was looking around online, and saw some of these have the "Fab Defense" name on the side, and "patent pending", and some seem not to. Mine doesn't,,,,,,,,,makes me wonder a little about a counterfeit unit, or maybe this is also made legitimately by others.
Several different mags seem to pop in and out okay, empty ones. I'm going to try a few with full loads in them, see if they are stable. Again, thanks.

If anyone else has one of these, I'd love to know your thoughts about them.