Depending on your altitude, and whether you actually have a true 1:9 (some barrels are slightly faster, some slightly slower twist) you might get past a 69gr, but generally that seems to be the limit for that twist in .223's.
Instead of buying a whole box, take a look at the Bullet Exchange thread under the Big Game Rifle reloading Forum. Someone might have the bullets you want to try.
The only way to really know is to shoot them.
All the best in your search!
Ed
"Not in an open forum, where truth has less value than opinions, where all opinions are equally welcome regardless of their origins, rationale, inanity, or truth, where opinions are neither of equal value nor decisive." Ken Howell
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