Read this page of our guide to The Last of Us 2 to learn how to unlock a silencer for your weapon. You will find out whether the silencer can be installed on any weapon model, and whether it can be used without restrictions throughout the entire game.
A silencer is a weapon upgrade that can be crafted. Unfortunately, you can't make silencers from the very beginning of the game, and that's because Ellie doesn't have the recipe required to produce it yet.
You have to wait until Seattle Day 1 you advance to the Seattle - Capitol Hill stage. It is one of the stages on the way to the headquarters of the Channel 13 television station. During this part you pass, e.g. a gas station. Follow the main streets until you come across the bookshop shown in the picture - you will recognize it by the LBGT flag hanging next to it.
Inside the bookstore, you will find a passage to the Coffee House cafe.
After entering it, find the Training Manual: Stealth.
Getting this training manual will unlock a new category of passive skills that you can buy for supplements - Stealth. Check out the first item from this ability tree - Craft Silencers.
Spend 20 supplements on this skill to get a silencer recipe. To craft 1 silencer, you will need 1 Rag and 1 Canister.
Each silencer has a very limited number of uses. Initially, a silencer lasts only 3 shots. After that, it is irretrievably lost and you will have to make another one. You should also unlock the Improved Silencers passive ability from the stealth tree - it will increase a silencer's durability from 3 to 5 shots.
You will play as Abby later in the campaign - she can craft silencers for the Military Pistol right from the beginning.
In Abby's case, you can also acquire the Upgraded silencers skill, which increases a silencer's durability from 3 to 5 shots. This ability can be found in the Ordnance skill tree. Check out the Training manuals and passive skills page to learn how to unlock this skill tree.
Attaching a silencer to a weapon
The silencer can only be installed on the pistol - it will not match any other type of firearms.
The good news is that you can attach and detach a silencer whenever you want to - do this by pressing the Triangle button. Removing the silencer is a good idea if you plan on having an open confrontation and don't want to use it unnecessarily.
Additional note: when using a silenced pistol, try to aim at the opponents' heads. This will increase the chances of killing an enemy with a single shot, making each silencer last longer.
Silenced Submachine gun
During Santa Barbara, the final chapter, Ellie automatically gets the last firearm - a Silenced Submachine Gun.
This is a very important weapon because unlike normal silencers, the one mounted on this submachine gun doesn't lose durability. You can use this weapon in the final stages to easily eliminate individual opponents without alerting the entire area.