I don't run around with those in the first place, lol. and aerodactyl, if you go into the prestige shop and use your coin for 'unlock gear" after prestiging once, you can choose to unlock the RPG permanently throughout the whole game, even after prestiging again (or so I believe.)
I'm Using it for the AK-47 (52 levels away, lol), It was always such a fun gun to use...