Hi otis,

It doesn't surprise me that the 100 grain bullet is most "popular"....as many people believe "fastest is always the best". Personally, in 6.5mm, I believe a 120-125 grain bullet has probably the ideal sectional density for whitetail sized animals. And that is what I use! (Though in the case of the 100 grain partition....the design of the bullet probably compensates for its lack of sectional density.)

I wouldn't worry too much about what is most popular....in my opinion....go with your first instinct and find a good 120-125 grain bullet that shoots well in your gun. And don't look back!

Good luck!