Unless you want or need to shoot the superheavyweights, you concerns may be unfounded. I have found that bullets in the 60 gr weight have done everything I expect from this cartridge. I limit its general use to 300 yrds. If you need to shoot something living farther, use more gun. On paper, you will begin to get alot of drift out past 350 or so unless you shoot the 75+ weights.
You mention 1 in 9 but 1 in 7 is a better rate for the true heavy weights. BUT You also mention the 243, do you have both rifles? If so your delime is easily solved. Shoot 40 to 64 grainers in your 223 and 70 to 105 in the 243!
You may even try the the slightly heavier bullets, you may be suprised. You will not hurt anything, worst case they wont be as accurate.
Good Luck,
CW