Anyone who shoots alot will eventually see that happen. I have seen it a few times over the years, and did it myself once(from the firing line at a silhouette shoot). We had a fellow at the range bulge a barrel one time. But it is my belief the the ram rod was not sitting on the charge. It appeared the rod was most of the way out of the barrel when he pulled the trigger. The ramrod did not go down range, it splintered right there. Check the barrel for bulge. If you do not know how, then have it done by someone who does.

Remember Murphy's Law. Tom.