Can these be done to a non Law enforcement stanmped AR 15 ?

They can be done to ANY AR. Not sure if there is more to your question or not, a barrel is a barrel is a barrel.

Not sure I understand your question-- If you want to put a 1-in-7 barrel in an upper, there's no problem-- The 1-in-7 twist was originally selected because it stabilized the M856 tracers (which were a little heavier) better than the 1-in-9 twist originally selected for the M855 ball ammo-- If you don't intend to shoot bullets heavier than about 63 grains, there isn't much to be gained by the 1-in-7 twist, other than that it's the issue deal-- But legal problems?? None I'ver ever heard of-- Hope this answers your question-- If not, perhaps you should restate it---

Yeah, I mean if you want to change barrels, which is the only way to get a different twist, than you can put on whatever you want. The length is the only thing you need to worry about. It has to be a total of 16" whether the barrel is 16" or with a permanent flash hider or brake makes it 16" doesn't matter, it just has to be 16". I won't get into SBR's or anything.

Yes, it isn't a problem in the least.

Ok to add to my origanal ? So I could by a model that has a 1-7 twist barrel and put it on a model that originally came with a 1-9 twist and it would be just like a LE Model then? Or their others things to it besides a flash hider /bayonet, col-stock,etc?