Peterson Cartridge 6XC casings are made to CIP external specifications. After producing their 1st "batch" of these 6XC casings, they noticed that there are some differences between 6XC casings made by Peterson, and those made by Norma. The main difference you will notice is that the internal volume of these Peterson-made 6XC casings is less than the internal volume of those made by Norma. As a result, you will likely need to re-work your load for these Peterson-made 6XC casings. Using Peterson Cartridge's internal ballistics lab, they were able to determine that 6XC casings from this 1st production run perform really well around the 2900 FPS accuracy node. If Mfg: Peterson Cartridge