My experience is a bit different from petemi's, but first, I need to ask, "Which CL-the 150 or 170?" It might matter. My Handi dotes on both bullets on paper. I've used both on whitetails-with happy experiences. I'm extremely impressed with the 150 gr. CL for general work on whitetails. It's consistantly accurate in my gun and the bullet seems perfectly balanced for its intended mission, i.e. I have yet to recover one, even on quartering shots and they seem to open adequately for quick, humane kills without ruining meat.
With respect to "penciling through" deer, I've no reason to doubt anyone's personal experience in such things. It happens--sometimes with even much more sophisticated bullets. My experience with the 150 gr. CL's is that they tend to leave a very modest exit hole (lung shots) that could mislead one to believe they're not "do'n the job". Inside the critter, it might be a different story. Personally, I've no problems with the performance of .30-30 CL bullets on deer size critters. In fact, it's my favorite projectile for that job.