On the Purdey side by side the pins do have a small hole right through them and are known as vent pins.This is standard practice on Purdey's and really is traditional so they've kept it.On the O/Us there are short flat retainers let into the back of the actions.As with the pins on the Boss O/U these limit movement and stop the strikers from spinning.Unless the cap is pierced there is no gas to vent.The way the strikers are shaped and the amount of protrusion it is highly unlikely that a cap will ever be pierced.
