Metallurgy Question:

Hardened steel does not generally deteriorate over moderate periods, especially not as short as ten years, providing it have been protected from corrosion. Strong magnetic fields and electric fields generated through or around the steel can have an effect, but this is highly unlikely. If your bolt carrier has been kept protected and oiled it should be fine. I have a shotgun that was made in 1740 which has lost none of its hardness as well as steel swords dating back to the 1600's that are still hard and sharp. You should not have a problem.