The only AR I have ever owned
- Colt model LE 6920. "NIB". :)
Modified -180 with aftermarket buttstock and barrel work:
Kurts Kustom Firearms "EvoM9" piston conversion. His was one of the first, before HK "reinvented" it for their upper. He was also known for his Bushmaster M17 upgrades. Kurt passed away 2009 but his work lives on!
Here's a BIY piston upper. Just goes to show innovation doesn't have to be complicated or expensive:
Now, way back when, ZM firearms made a gas-piston upper and went one step further and relocated the recoil spring over the barrel, so that you do not need a buffer tube on the stock, meaning you can use a folding stock in its place. Today, ParaOrdnance has bought their design and uses it for their AR:
Very advanced design. In my opinion, one of the BEST AR designs. Now that piston ARs are being rediscovered, this has received more attention and seems to be getting good reviews.