I assume you mean standard R11 irons, there is only a driver, 3 wood and hybrid available as an S model. There have been plenty of requests for the S irons but since they don't exist in real life they're unlikely to show up here.
Backspin can knock a lot off the distance, especially if you hit slightly under full power. If you take your 180 club for a 170 yard show and use full b/s it is very easy to land around the 155 mark. There is a chart somewhere here with distances for full power shots with various spin.
One other thing, did you clear your Flash cache when you changed clubs? You should always do that when you change gear.