The OP could buy a .38, find a local Hand loader and pay for some soft target loads for a few hundred dollars vs. a young fortune for a 1 millionth speed flash even if one could be found. The old rule is that if a shot feels or sounds strange, open the action and check the barrel! Having some experience with CB caps, your incident surprises me. The pressures needed to bulge a barrel shouldn't be there.
This happened around 40 years ago, and I did shoot both CB caps and full loads, and perhaps I'm confused about the exact sequence of events, but the end result was from a bullet not exiting the barrel. It's a good thing it was only a .22.