Gunslinger Achievement

The pistol is an underutilized weapon but can be very useful in tight situations. A first in the series, the M1911, which is unlocked by default, has a suppressor attachment already available and equipped, making it more powerful than and just as silent as the Welrod (which has been the standard suppressed pistol in previous games). To unlock this achievement, you need to cumulatively kill 150 enemies with any combination of the pistols listed above in Master of Pistols (15G) throughout all game modes.
 
Refer to the ‘Mop Up’ section in the roadmap for a farming method to make this go a lot quicker.
 
To check your progress, press then navigate to Service Record > Medals > Weapons and Items and look in the first section to see your medal progress.
 
Note: For Master of Pistols (15G), you are required to perform 50 ghost kills with each of the six pistols listed above, so this will unlock naturally while you are progressing towards that.