Actually, the bore is 1-in-28" . I measured it myself and had it confirmed by a phone call to Thompson/Center' s service dept. I wanted to get an owners manual for it, anyway, so I asked the the service agent them.

Like I said, my T/C grouped better at 100 yards than my Knight does. My dad always shot the 460 grain Hornady conicals with good accuracy when he hunted with it. I just thing that the sound I hear is the bullet impacting the target, but all the bullet holes are round and even so there isn' t any evidence of instability at that range.

Mike