If you shoot enough of the 38's in the barrel to make even the smallest flame ring, you will have problems extracting 357 cases...
I would think that with the length of the freebore on a TC, the 38's would be inaccurate due to the amount of bullet jump... I've had several 357 barrels, and anything close to standard length loads wouldn't shoot, but when I loaded the bullets out, I started getting better accuracy. I think there are much better caliber choices in the Contender.