You sure it's your factory barrel? I'm sure it could be but, my 243 700ADL was the second worst shooting rifle I have ever owned, #1 was a Rem mod 7.
After completely opening up the stock and completely redoing the bedding including adding pillars and putting on a steel trigger guard, it shoot's very well. The barrel had nothing to do with the worst bedding job I have ever run into.
The mo7 on the other hand no ammount of working on the beddin g would solve it's problems, I got rid of it. On the mod 7 I wrote Remington and was told they expect that 3" a 100yds is adequate accuracy, for a 223! I haven't bought a new Remington since. Been close to 25yrs I guess.