I went to Colorado to visit my wife's grandparents this last summer.

I got to do some slinging on a grain (I don't know what type) farm.  Thinner air and wide open spaces really seemed to allow me to throw like I've never thrown before. 

They had a barn there that my inlaws were shooting with a 3-man-sling.  For those of you who don't know what I'm talking about, imagine a giant slingshot. It was homemade with surgical tubing.  It was a bit bigger than some of the commercialy made ones.  They knew about me and my slinging and they wanted to see how my sling would compare with theirs.   The barn was just within their effective range.  I was able to shoot well over it using a 41 inch sling with a figure eight style of throw. Of course, I was shooting smaller rocks.  Later I walked over closer and was able to shoot a rock through the barn.  I'm not sure how impressive that is going to sound because the barn is real old and is starting to rot. They were able to pierce the barn from there maximum shoot range.  Since I was shooting smaller rocks, I had to get closer to get penetrating power.

I remember Knollslinger said that he started slinging in Colorado and he was able to do better than 1/4 mile.  Well, I've never slung better than I have when I was in Colorado. The thin air seems to make a big difference.  Part of it is there is so much space there that one doesn't have to worry about hitting anything.  The thin air really makes a difference. I also found that it is harder to play the harmonica up in the mountains.  One has to exhale faster to get the same result one is capable of getting at a lower altitude.  As a consequence, I find that when I run out of breath more easily when I'm up in the mountains. It makes it harder to play a series of long exhale notes.