i have 99C/CDs in 257AI, 25-284, 6.5-284, and 338-284. As noted previously, they all run into COAL issues because of the magazine length with longer/heavier bullets. The first two do fine with most bullets under 115 grains, the third with most bullets 120 grains and under, and the third with bullets up to 210 grains. I would do the 25 Souper or 6.5 Creedmoor if I was going to rebarrel a 99 today. That said, I think that the 99F that I had rebore/rechambered from 243 to 260 is about as perfect a 99 for deer hunting at reasonable ranges as a person could wish for.
