I purchased a used, rare caliber Remington two years ago. This rifle did the same thing. Come to find out that the action was bedded without the safety being cycled. When the bedding hardened, the bedding was obstructing the full movement of the safety switch. I removed the obstruction with a roto tool and have had no problems since. There may have been a small piece of the stock that wasn't properly inletted to cause the unsecure safe function.