I have a bottomless portafilter on my Gaggia Classic, and I very rarely get a nice pour like in MrBlobbys photo, its usually either a very slow drip or a torrent, or I get lots of litle jets of coffee coming out at various angles.
I have an Iberital Burr grinder, never sure how fine to set the grind, and never sure how much coffee to put in the portafilter or how hard to tamp it down.
Any advice would be appreciated.