I'm going to be getting a piston driven upper that doesn't require a buffer/spring, so I'd like to utilize a folding stock. From what I've gathered, I could only find the LAW Tactical folding stock adapter, the US Machinegun Folding stock adapter, and possibly an ACE folding stock adapter. The LAW Tactical one looks super solid, but it runs $200. That seems like an awful lot for just a little bit on hinged metal. The US Machinegun adapter is only $40, but from the youtube videos i've seen, it looks pretty flimsy with a lot of up and down play/wobble. The ACE folding stock adapter, I am kind of unsure about. Maybe I'm a little slow, but I can't figure out exactly what I need to just screw my UBR on one end and the other into my lower. Are those adapters as solid as the LAW Tactical ones? Any other adapters that I'm missing?