Are you going to have the choke opened or have tubes installed? Last year I bought a 20ga m37 with a Full choke and took it to a shop with a pull-through gauge to confirm the constriction. With cheap shells the gun does not seem to shoot so very tight (I have not patterned it to check though) and it's worked fine on Pheasant and quail. Unless you're restricted to hunting dense cover and need an open choke it might be worth patterning to check just what the barrel can produce now.