Could be that it was simply too much for the pressurized filter basket. I might need to upgrade to the non-pressurized basket sooner.

Stalled my espresso machine this morning, so I guess my grind/dose/tamp are approaching the machine's limits.

I'm pretty sure I'm still buzzing from my coffee this morning.

Managed to get 14g of coffee in my portafilter this morning with a double tamp. Best double shot so far.