A friend and I were out shooting today, me with my GLOCK 19 and him with a S&W 640. He has just fired his five rounds when he attempted to eject the empties, only about 1/3 of one case ejected. The case had split all the way around leaving 2/3 of the brass in the chamber. We tried to tap it out from the front with a dowel, but it wouldn't budge.

The ammo was standard pressure Federal Hydrashock.

I’ve had that happen a couple of times with reloaded .38 cases (that were obviously reloaded too many times).  It happens at the ring that is knurled around the case, which is a natural weak point.

Never seen it happen with new ammo.

.38s have powder in them?

I had that many years ago with Hansen (Prvi Partisan?) .357 Magnums in a Colt Python. After I fired, the cylinder was stuck. Really stuck! I could not open it, turn it and was quite puzzled. When I took the gun home and held it against the light, there was no light in the barrel / cylinder gap.

I tapped out the almost 1/4 inch long case mouth  It showed even rifling and was conical! Those were crimped and laquer sealed cartridges. I wondered if they glued the bullets in!