For heavy loads of larger shot, such as Nos. 4 or 5, use a bit less constriction. For a lighter load or smaller shot, such as No. 6, you might be able to use a tighter choke. In choke tubes, 10/1,000 inch can make the difference between a great pattern and a mediocre one. Also, some guns shoot better with a porter choke, which grabs the wad as it exits the barrel and keeps it from driving through the shot pattern.