Hornady Lock-N-Load Headspace Gage 5 Bushing Set with Comparator

Without this tool you are basically reloading blind folded. I originally bought this tool after I experienced a case head separation after just two firings on a .308 with a match chamber. Being that my rifle is a semi-auto FAL, I first thought that it was the violent extraction of the brass that caused this. So when I got home I put a sized brass case next to my fire formed case and I could visually see the shoulder being set back a lot more than it should be even though I was setting the die per manufacturers instructions. It turns out that by oversizing the brass I was causing and exessive headspace condition that greatly reduced the life of that lot of brass. So after I bought this tool, I was able to set the shoulder back just .002 and my groups shrank from around one inch to a consitent .75 or better using 5 and 10 shot groups. Trust me, without this tool or one similar there is just no way to accurately reload. After the first use the extreme spread on my loads dropped from 15-25 fps to 8-12fps which was incredible.

Just bought based on "review" in Zediker's reloading book saying the Stoney Point Headspace Gauge was "the best." That tool is no longer available but, apparently, this is the same tool under a different name.