What bottom metal? If a 9" twist, for a lightweight build I'd go Wyatt's box and load the 180 ELD. If forced to work with a <2.9" mag box, load the 162 ELD and call it a day. The 140 TTSX at ~3300 fps has also been a fantastic 0-300 meter load for me.
Haven't used the Horn 7WSM brass, but I've used some of their other offerings, and it's generally quite good stuff. Not Alpha or Lapua quality, but about as good as the best RP/WW brass I've run across.
