The 300 Ham’r cartridge is over 10 years in the making. The extremely short history of that making is Bill Wilson took the 7.62×40 case developed by Kurt Buchert, lengthened it by .040″ and stuffed it full of Hogdon’s new CFEBLK powder. He then pushed rounds from 110gr to 150gr through a 1:15″ twist barrel. The results were, at least on paper, very impressive. The velocity gains claimed over the 300BLK, and the corresponding energy delivered, were significant enough to justify the caliber.