I found this site that shows pics of the fire that different primers give off. It's kind of interesting. Who knows how accurate the testing was.
http://images.google.de/imgres?imgurl=http://www.bjonessights.com/PMC_Large_Rifle-a.JPG&imgrefurl=http://www.bjonessights.com/Primerpix.html&h=480&w=640&sz=32&tbnid=OyVLHJHc42kBjM:&tbnh=101&tbnw=135&hl=de&start=6&prev=/images%3Fq%3Dprimer%2Bflash%26svnum%3D10%26hl%3Dde
Good shooting
Greg
http://images.google.de/imgres?imgurl=http://www.bjonessights.com/PMC_Large_Rifle-a.JPG&imgrefurl=http://www.bjonessights.com/Primerpix.html&h=480&w=640&sz=32&tbnid=OyVLHJHc42kBjM:&tbnh=101&tbnw=135&hl=de&start=6&prev=/images%3Fq%3Dprimer%2Bflash%26svnum%3D10%26hl%3Dde
Good shooting
Greg