The 510 GNR was developed by Gary Reeder from Rheeder Custom Guns, Flagstaff, AZ around 2004 and is based on the 500 Linebaugh case that was shortened by about 1/10th of an inch. It allows for the cartridge to be downloaded to about .500 Special ballistics and upward to 500 Linebaugh, which makes a very versatile cartridge for a variety of hunting/shooting conditions.