I may have to give T/C a call to find out for sure. I'd considered getting a .300 Whisper barrel for my Contender, but figured I could accomplish the same thing with a .30-30 barrel. My plan is to use 240gr SMK bullets at around 1050fps (with a suppressor), but it will only work if the .30-30 barrel is 1/10" twist. I like the idea of using the .30-30 over the .300 Whisper as it has more case capacity, so I can still use it to hunt deer with standard 150-170gr loads. Plus, I won't have to deal with forming brass. All of it is a moot point, however, if the twist isn't correct.