Alekhine's Gun

This trophy is awarded for completing Mission 3. Your rating is not important here but completing it killing only the target will count this towards the 11 missions needed for the Legendary trophy, so see the description for that trophy for links to videos showing how to complete them killing only your targets.

Note that this mission is the ideal place to obtain the following trophy:

 Locksmith - Perfect lockpicking attempt on a lock with at least 4 locking mechanisms.