Taz
Not many 7mms at all are shooting at Williamsport.
There may be 4 or 5 fellows using the 7mm and they don't win very often with them and I'm not sure why?
There are many good 7mm bullets being made that have high BCs and should shoot well.
The most used cartridges seem to be the 30 Cals (Weatherbys and Improved) and the 6.5/284.
Many Weatherby improved cases are used but most are 30 Caliber creations. The 308 Baer, 30 Goodling, 300 Weatherby are just a few of them.
Hope that helped.
DC