In the 28" Pro Hunter barrel, the STW should be a formidable 7MM. In a 24" barrel, it's not much faster than a 7 Rem Mag. Pressure is pressure. Doesn't matter a whole lot if you are loading a 7MM-08 to 55K or a 7MM RUM to 55K. There shouldn't be any problem with rechambering as long as you don't wind up with a little bump where the old shoulder of the 7 Rem Mag was - you can look at the cartridge specifications and try to figure the diameter of the STW's case at that point - but sometimes factory chambers are a little fat and often gunsmith's reamers are a little tight . . . . . Problem with the Encore/Pro Hunter is that you have no ability to set the barrel back if this gremlin raises its ugly head. If you don't already have the barrel, a safer bet would be to start with a 7MM-08 barrel.