I don't know why. My buddy (honestly a buddy and not me ) has recently acquired a new 7RUM with a 1/12 twist barrel. He wanted me to put together some different whitetail loads so he could shoot it up. I know that is an awfully slow barrel but I've only loaded for the 7mag so I don't know how the extra powder will change things. I was thinking of using some 140 Bergers or 139SST. I wont be pushing the envelope much and will be getting the most accuracy I can out of the loads. Anybody have any better bullets to try with this slow twist? Also with the MV of 3200-3400 (guessing) Will I need a bonded bullet? Something that won't fall apart with such speeds. He probably won't shoot much more than 300 yards. Also if you have a pet powder I'd like to try it out. I was going to go with the H1000/Retumbo 180VLD combo but with that twist I don't think so.