Originally Posted by urban
...is there any good reason to go with a piston system
Forget about all the other comments on this thread. The real answer for why there are so many of both is this:
1.) a lot of people had regular AR's and wanted to buy something new and different.
2.) a lot of people saw their neighbor buy a piston AR and decided they needed one, too.
3.) people have too much money to spend.
There you have it. People always want bigger, better, newer, different. You can get into all the details about how the two types work better or worse for shooting guinness world record-level groupings, or how one is more reliable than the other when stuck in the jungle/desert/mountains/etc against an army of blood-thirsty enemies soldiers... but, of the millions of AR-based rifles in civilian use, how many are shooting world-class matches at 600 yards or battling to the death in the demanding climates of wherever?
Most people take their rifle to the local range and send a few boxes of lead towards a paper target sitting 100 yards away. Then they go home, have a beer and watch TV. Flip a coin to decide, because either rifle will be just fine for them.