RSVP2RIP said:
The ammo was factory Winchester Silvertip.
When I shoot current factory Silvertip in my 9x23 I've seen early signs of that happening, too. Mine don't quite pierce like what you decribed, but they do flake off a bit. Once in a while I had the primer material flake off and clog up the firing pin hole. My top end was a complete build by Jim Garthwaite using a Caspian slide.
Like rcmodel suggests, the firing pin needs to very closely fit the hole when you're shooting 9x23. That round is really high pressure, and the primer is the weak link in this particular cartridge. If there is any space for the primer to expand back between the firing pin and the firing pin hole, with a softer material primer it will flow back.
I really don't know what Winchester did, or what they're using now to assemble 9x23 Silvertip rounds. But the primers are most definitely too soft with some of the boxes I bought about 4 years ago. When I load 9x23 at home, I use small rifle primers. Period. The challenge is if your mainspring is a little light, or the assembly of your 1911 makes for a light hammer strike, it won't have enough force to set the primer off. Go to a softer primer, and the high pressure of the 9x23 will tear it up.
Some of those 9x23 Colts weren't made quite the way they should have been to shoot the 9x23 properly. The round was still in its early stages of development, and Colt didn't do too much besides re-spring 38 Supers and drill the chamber to 9x23 dimensions for most of what left the factory. The tolerances on the fit of certain parts, like the firing pin, are a lot less forgiving of a sloppy fit.
Measure the firing pin hole, call Brownelll's, and replace the firing pin with something that fits better. I also avoid Winchester Silvertips in mine these days, too. When I run 9x23, I shoot reloads in mine.