If a bullet is going fast enought it wouldn't drop at all from 100 yds to 200 yds but with a 30/06 I wouldn't think they would go that fast. As far as groups go different bullets group in different places. I just recently shot one of my rifles at 100 yds with two different bullets at pretty near the same volosity. One grouped about 3" higher than the other group. Different bullets can make a difference. Sometimes they all go to the same point of aim if you get two bullets that have the same flight design and same powder.