I have a 7wsm barrel I'm using to build a more pack friendly hunting rig than my current 27" varmint contour 7wsm. As hard as WSM brass is to come by I have a bunch of 270wsm. I was wondering instead of fire forming the 270 brass if I could just have .040" taken off the new barrel and end up with a 7/300wsm and for go any fire forming in the future? Or am I missing something?