If you are talking about the Berger High BC flat base bullet that used to be called the Low Drag flat base I have used them but not in a 243 win. I have used them in a Ruger VT in 6PPC. The rifle has a twist of 1in12 which is recommended by berger for these bullets. I have used them on grounds hogs from 10 feet to 500 yards. Mine are moly coated and I was running them at about 3200fps from my rifle. On the ground hogs I took the time to look at the terminal effects where outstanding. My bullets are from the older lots(match bullets) before they where classified/manufactured with a larger hollow point opening and called varmint bullets. I had to load these one at a time because the short fat PPC casing and these long pointy bullets would not reliably cycle from the magazine. I was able to get sub 1/2 inch groups at 200 yards with this bullet/rifle combo. I know this isnt a true answer for you but since I got great terminal effects from a PPC the 243 win should produce much better terminal effect.