Great stock...*cough*... brace :d - DoubleStar Strongarm Pistol Brace

This is an excellent brock, excellent stace, excellent bstace, excellent something you should never shoulder, but also sometimes, because 3 letters told you can, but you also can't as they said it.

Gladly for times that you do shoulder this, it is a hard aluminum, so hard in fact that it will never bend, it will never deform.
It's the most rigid piece of metal I ever owned for an AR, and it's well machined and polished. It's dense and not hollow.

I had it on my MK18 at home build, before the AFT fiasco, and braces becoming illegal, and becoming legal again in next month. At that point I disassembled my MK18 clone and moved on with my life lol

This brace is truly wonderful, and it served me well while I still had my MK18 imitation.
Thing to note: this WILL go on your rifle tube losely, so what you can do is roll electrical tape carefully 3-4 times around the rifle tube (not carbine buffer tube, rifle for A2 rifles) and it will allow you to create enough space to tighten the brace then as you push it on the electrical tape portion.

The way I managed to do my pistol was to use that long rifle tube with a spacer inside for JP Enterprises Silent Capture spring, then I filed the tab on end plate just a tiny bit. So, not to damage the threads on the rifle tube as you add the end plate before the rifle tube. It will actually work, and you can use regular buffer end plate in conjunction with
rifle tube that has no adjustment positions.

Then it makes your gun look like a SIG MCX Rattler, it was a dope look for me, I had Aero Quantum handguard 9", and 10.3 barrel with A2 flash hider.

Man, it was a good build before AFT shenanigans. I miss the pistol, but I don't miss feeling like I am under the microscope every year, because "laws" change on a whim.