During certain fights there will be a Jack-in-the-box box which contains one of the three power ups (Launcher, Tommy Gun and the Spreadshot). You will randomly get one of these weapons from the box for a short period of time. Melee (press ) the box to activate it. All you have to do is kill 10 enemies with the weapon in the allotted time for the respective achievement to unlock. To make it easier purchase the upgrades to make the timer last longer. Holding down the instead of tapping it may make this achievement easier especially for the Tommy Gun.