I'm sorry to hear about your incident sir - but, I'm glad I saw this post. Up front, I am not a ballistics expert - but 147-g 9mm is kinda similar to 180-g .40SW. In order to meet cartridge overall length requirements - both bullets have to be seated deeply into their cases since they are longer than lighter bullets. This leaves a smaller case volume and greatly increases the potential for higher pressures. Pure SWAG, but the rounds were probably loaded to the correct length, but since they were reman so they probably used diff brands of cases. Different brass, different case thicknesses - and all it took was one of those rounds to hit the feed ramp too hard and it deep-seated the bullet. Pressure sky-rocketed as a result and you had your incident. Again, this is speculation. Back to why I'm glad I saw this post - I have some Federal factory 147-g that I'm going to gather up (almost two boxes) and use only in my CZ-75. I gave away my last box of 180-g .40SW and I'm never going to buy any 147-g 9mm again...

Edited to add: This could also have been the result of firing out-of-battery - with the slide not completely closed. Never having owned a Shield, I'm unsure of why that might have happened. I do know that firing OOB was a big enough of a concern that SIG made some design changes to the newest P320's to help prevent it. All of this said, previous comments about 'Glocked' cases sounds scarier and scarier.