That will depend on which version you get. Later guns appear to have come with 1:48 barrels. Any barrel with QLA should be a faster twist, as the feature is meant to hold longer projectiles straight for loading. No reason for it on ball-twist barrels, yet I had two of them marked Pennsylvania Hunter with QLA and they shot 300gr Traditions bullets well. I measured one with a tight material around a jag and came in around 1:50 so figure it was 1:48. A barrel with 1:66 from T/C should be stamped as such.