The 9 twist stainless barrel is probably the best choice per your comments above.

and have been shooting my normal 100m range and the best group I've been able to get is .71
Your above quote is the reason I responded to your thread. The same thing happened to me and I couldn't explain it. My groups opened up to about .750 moa @ 100. It seemed like all of a sudden. I thought it was me or something to do with the scope. My rifle was as accurate as yours. I use my 223 for practice, so it had a lot of rounds down the tube.

Then one day a bell rang in my "brain". I realize how many rounds I had down this barrel. I decided to change the barrel and with my first few groups, I had my ole rifle back. I was one happy person as this is one of the oldest rifles I have.

Just my .02, Dennis

Their going to go, it's just a matter of when.