Here's an interesting article for the reloaders amongst us. I'd read an article about this experiment but not the original article. The basic story is that a guy set up a shooting lane in his warehouse that was essentially a sterile environment. No wind, mirage, temperature fluctuations, or changes of lighting conditions. He then spent years testing various elements of reloading and gunsmithing theory to see what really worked.
http://precisionrifleblog.com/2013/10/1 ... -accuracy/
That link has a summary of the original article as well as a link to download the original article.
The results were extremely interesting. Some of the techniques he used to reload fly in the face of what is commonly considered the "right" way to do things but his results speak for themselves. Certainly something to ponder.