Oh so now you think an AR-15 is considered a precision rifle from the factory without being reworked by a qualified armorer? Yes it does not position anything upward it positions it together. First of all you need to remember the planet is a sphere. What is up to you here is down to somebody in Australia so the terms up and down are completely meaningless but gravity is the most constant force in the physical universe. So where is your documentation on rifles that have play with aftermarket fixes? Apparently you are just opposed to the idea that I have improved one of my rifles so inexpensively. There is no way possible take a dial indicator to an assembled rifle. The accuracy of the rifle is solely determined by the upper in an AR platform I would think you would know that. The play between the upper and lower was merely an annoyance it does not affect accuracy in any way. Flat feeler gauges and wire style gauges is how you check for what you're talking about. Explain to me how you set a rifle up in a jig and rotate it 360° in all three dimensions with a dial indicator on it. Obviously you've never worked in any type of machine shop. Yes when my upper and lower are jam together tight and held there by the zip ties the relationship on the front pivot pin and the rear takedown pin is the same every time, much more so that without the zip ties. As far as competition goes that it is much more determined by the skill of the shooter be his rifle tight, have .004 or even up to .012 the mil spec requirement. I'm sure a U.S.Navy SEAL sniper could out shoot both of us regardless of what piece of junk he was shooting and regardless of what a fine rifle we had. You live in a world of theory and documentation.