Generally tamping harder is not a great solution. It seems it can lead to channelling etc.
So I’d either grind fewer beans on the finer setting or more beans on the coarser setting.
WDT makes a huge difference. @Sainsburys_Ed get a naked portafilter and watch your coffee spray everywhere, then use a WDT and the channelling and spraying will almost completely stop.
I know what you mean, but I'd argue it's a variable worth having a go with. Although your reply has me tempted to grind finer and tamp softer for the sake of experimentation.
Generally tamping harder is not a great solution. It seems it can lead to channelling etc.
So I’d either grind fewer beans on the finer setting or more beans on the coarser setting.
WDT makes a huge difference. @Sainsburys_Ed get a naked portafilter and watch your coffee spray everywhere, then use a WDT and the channelling and spraying will almost completely stop.