The only thing I can think of worse than the police finding your prints on a murder weapon is them finding your prints on a murder weapon you destroyed.
Police would expect to find your prints on a murder weapon if you found it and picked it up (which you should not if you find a gun randomly laying somewhere). However there are a lot of ways to tell if you were actually shooting the gun which would be more important to them. Besides even if it was used in a crime it would take rather daunting odds to link you back to such a crime, even with your prints on the weapon.