I've used a few of Rocky Gibbs cartridges over the years. Still have a 240 and 7mm (might still have an 8mm too, have to look). Without going to the longer Hawk cases, they are about as "improved" as you can get the basic 06 case. They do require fireforming of the cases, and a little more difficult to do then a properly chambered Ackley. Generally, they will push bullets of like weight slightly faster then an equivalent Ackley/RCBS cartridge. I like them, but unless you handload, you won't be shooting it much. Greyback Wildcats stateside used to make brass for them, but I don't know if they still do. Unless the rifle comes with dies, or you really want a Gibbs cartridge, or the rifle is dirt cheap, pass. - dan