If you have several hundred thousand meseta to spare and don't want to wait for 10* weapon drops, log into the personal shop on the visiphone terminal and filter the search settings to show 10* weapons, sorted by lowest price first. Pick up 10 weapons or however many you need, and then convert them into ex-cubes at the swap shop, which can be accessed via the shopping cart icon in the main menu.
Take your newly acquired cubes to the second floor of the shopping plaza, and as seen in New Paralyzer's solution, pick any of the PB devices there. Once activated, go on a mission (any difficulty will do) and fight until your mag emits a glow, indicating it's ready to fire.
Upon using it, the achievement will unlock.