Here is another thing that compounds the issue of a misaligned cylinder or too-wide cylinder gap: reloaded or handloaded ammo that has had a little sliver of lead "shaved" from the base when being seated in the case during loading. I have noticed that the slight flare at the mouth of the case varies if overall length varies with case to case, and sometimes a case mouth not expanded enough will catch the lead bullet base off center and chip off a piece of lead that later gets pushed around the bullet and ends up being a loose particle somewhere around the case mouth, and free to fly upon firing, often getting blown out the cylinder gap. In other words, try jacketed ammo, or a different brand of reloads, or more care if loading one's own.
