The barrel band retaining springs have an attached thin metal rod that is inserted into the stock, under the barrel. There is a small hole on the opposite side of the stock (sometimes filled with shellac or grease). Using a very narrow and long drift (even a small blunt ended nail will do), slowly and carefully tap out the rod.
These springs can sometimes be fragile, so don't attemp to twist it out or pull up on it. That can cause the spring portion to break off from the rod.