I'm just wondering if it's okay to dry fire an AR-15. Whenever I take mine out, I of course open the action to make sure it's empty, but in doing so, I've cocked it. So my question is, which is the appropriate way to store an AR-15:

1) Store the rifle with the hammer back with the safety on

or

2) Store the rifle with the hamer forward (by dry firing it) with the safety off

I just pull the charging handle back until the bolt carrier is in the right spot, drop the hammer and then ride the charging handle forward so it's not stored cocked and I'm not dropping the firing pin on an empty chamber.  It's not likely to matter though.  It's intended to be used by people who are a lot more abusive to their weapons than leaving it cocked.  Anyway, worse thing that could happen by dry firing is stress the firing pin.  Not likely, but under $10 to replace.  Likewise, storing it cocked could at worse weaken a $2 spring.  No biggie either way.

Store everything with the springs as relaxed as possible (hammer down).

I agree with qwijibo about the costs but it's a PITA to change trigger springs compared to a firing pin.  Bigger pain when your on the firing line and have to do it.

We used to dry fire practice with our M-16's pretty regularly so the danger of damage is probably overstated.

Even so, as an extra bit of insurance, I keep a snap cap in the chamber of my AR-15's and keep them stored with the hammer down.

And just in case that's not enough, I keep a spare parts kit in the buttstock compartments of each rifle.

just dont dry fire with a 22 kit installed or on anyother rimfire for that matter

When I was in Boot Camp, our M-16's were hung up and locked to our racks(beds) by a cable through to ejection port and out the magazine well. This meant the the bolt was always locked back to the rear and the hammer stayed cocked when we weren't handling the rifles. We stored them that way for nearly three months. We also dry fired them on a regular basis. Granted the USMC has the spare parts and armorers to repair abused weapons. I store my personal fire arms uncocked.

Dry firing an AR/M16 will NOT damage anything.
Dryfiring any rimfire is a bad idea, but centerfires tend to have no such issues. There may be some exceptions, but the AR is not one of them.

You can dry fire a ar15 all day long and it wont hurt it at all. In basic training you'll dry fire a few hundred times before you ever see a live rnd.

Not to mention the standard function check for this weapon involves dry firing half a dozen times in a row...  Built to last, don't worry.