I have a 1913 vintage 12 ga field grade. Been in the family 4 generations now. Always been in great mechanical condition. Last few outings, the safety, if in the forward fire position, will return to safe if either barrel is fired. You have to push it forward again to shoot the second barrel. You can push it to fire and not shoot and it will return as designed when the gun in opened. Stays in place if fired in the rear position. Any ideas what might have gone wrong? Has not been worked on or tampered with.
Jim it is very possible the safety spring is weak or another possibility is that your thumb is on the safety and the recoil is pushing it to safe. The spring could be fixed by slightly bending the notch where the safety engages the safety slide but it means taking the stock off. As the gun has been used more and more, the spring could be getting weak and now your thumb is pulling it back. Just a thought