The 14 twist is going to be a PIA with non-lead.
IMO Go light, go fast. It is what has worked for me in my 12 tw 223.
What are you using now?
If it were me:
Go to JBM - Bullet Length List
and find your current projectile.
Then go to JBM - Calculations - Stability
and find the stability.
Then go back to the bullet length and find a Barnes that is similar length not weight.
Then go back to the stability and try it to see if your stability is equal or higher.
You will be able to run the Barnes faster as it will be lighter so stability will go up.
For me, for non-lead stablity of 1.8 or higher works, lead is good at 1.5 or higher.