I recently bought a new-to-me Beretta 390 and just got around to patterning it this evening. I tried a Hastings extra-full and full with a few different loads at 35 yards. Below is a pic of the best pattern. The paper is 24"x24". The extra-full was kind of stringy with every load.
That's shooting with a full choke using Federal 3rd Degree 3" 12 gauge 1 3/4 oz (20% Flitestopper #6, 40% Lead #5, 40% Heavyweight #7). This load was also the only load that was truly centered. I double checked by shooting it twice.
3rd Degree shells were kind of expensive (at least for me) but I figured I only will be shooting a few times anyway.