I'm still a bit of a newbie myself and still learning as I go.What I have learned to acquire a larger rim and spring,using 500 F heat,is to allow the dough ball to get sort of BIG with gas pockets,while warming up before use and rising at room temps.Do not over ferment or inflate the dough!
Using colder dough,just does not seem to let me shape nor stretch as well as a much warmer dough does.
It is true,a very hot oven can make the rim explode and rise,as we have seen on here,sort of like Neo-style pies,but when cooking under 550 degrees,I was not able to get those rim rises nor spring with much ease.
Take a dough ball and let it warm up in the room and if it does not rise that much,put it near a heat source and see if that helps.I put the dough in the bowl next to the oven as it warms up.That helps alot.
You may need to oil the dough a little to prevent it from forming leather skins or scales.The larger in size and warmer the dough ball rises,the larger rim I am able to make.
When the dough balls grows BIG before use,I use a floured surface,and with floured hands,I put the dough down and shape it carefully,pressing the center of the dough down and pushing the air pockets or bubbles toward the rim.If you have alot of air pockets or bubbles,some will pop.The key is to ensure the rim gets most of them and is not punched or flattened down at all.
Then after that,I lift the dough up and with 2 fists,I shape the dough larger and larger,while keeping the rim at ease.A very warm dough is sometimes too elastic,so make sure it does not fall across your arms and tear someplace.Put it back down if it stretches real fast,then do it again until its the size you want.
I know this is not a normal way of doing pie shaping but it is what has worked for me.This takes a bit of practice and trial pies.
Look at Jeff Varasano's pictures on his website...here is a perfect example of shaping the dough and the rim,and he was using extreme heat as well.My method is similar,but using less heat and longer cook times.
Look how the dough rim was shaped.http://farm4.static.flickr.com/3144/2629734379_4fcb086244_o.jpg