"New" is relative, current production 223s since sometime in early 2007 have been 1:9" except for the Superlight, anything older could have either. Just because a frame was made in 2007 doesn't mean the barrel was, they make barrels in runs of up to 500, the ONLY way to know what the twist of a barrel is for sure is to check it with a rod.

And even then, there's no guarantee the 1:9" will shoot the longer, heavier bullets, there have been lots of 1:9" barrels that wouldn't shoot anything heavier than the 1:12" barrels would, shoot it with the load of your choice and hope for the best.

Tim