Money well spent - SB Tactical SBPDW Mil-Spec AR-15 Collapsible Stabilizing Pistol Brace

For the price of a $200 SBR tax stamp and a basic sliding stock, you can buy this. No paperwork, no long wait, no NFA garbage, it's a BRACE. For PISTOLS. Or whatever else you want to put it on. Feels solid, looks cool, not as short as the Maxim, but not as expensive either, keeping it simple with a normal buffer tube. Doesn't need tape to stop sliding around like the cheaper sig braces