I’m no expert, but here is my experience with this issue. I inherited an old CVA Hawken with the same problem, but with double triggers. I tore the lock apart and polished every part. No dice, didn’t help. I have revisited it several times and have finally decided that the lock and trigger mechanism are not aligned properly. Only thing I could come up with and I’m not going to attempt a major overhaul on that old rifle. Hopefully one the experts here will chime in and give a better answer. If they do maybe we’ll both benefit.