Take your slide that you received from us or whoever you ordered it from, unpack it and set it aside.
For assembling a slide, you won't need much tools such as a study thin blade knife or small punch.
Take your slide completion kit and familiarize yourself with the pieces.
The first piece I like to install is the channel liner which is a plastic liner that goes into the firing pin channel. It protects your firing pin assembly from wearing against the inside of your slide. You can take an installation tool, such as the metal ones made or use the ones that come in kits which are usually a plastic tube.
You align the liner on the tip of the tool where it fits and place it inside the slide. You push until the liner does not move anymore.
The only Glock model that does not require a channel liner is the Glock 42 and Glock 43 single stack models.
Next, we assemble the firing pin assembly.
Some kits will come preassembled and some will require you to assemble it, which doesn't take a lot of work. After you assemble one, you'll know what to do. The spacer sleeve that goes on the firing pin needs to have the open end facing the rear of the firing pin. The "solid" non-open face needs to have the spring against it. You'll need to compress the spring slightly, avoiding pinching the skin on your fingers, and slide in the two piece cup assembly inside the spring to press against the other end of the firing pin to hold all these pieces in place.
There are tools that allow you to do this quickly and easily if it makes you nervous.
With our firing pin assembly down inside the slide with the installed channel liner, next we install some remaining pieces.
The firing pin safety which has a rounded face and has a spring in the rear can go in the hole in the bottom of the slide. You will need to push up slightly, with a punch or small screwdriver, on it to put the extractor in the frame hole but be careful it is not completely secure until the next piece is installed.
Next you'll need to assemble the extractor depressor plunger which is three pieces - a shaft, a spring and a tiny plastic loaded chamber indicator (LCI). You'll need to flip the spring to see which side fits the best on the shaft.
Next put that in the tiny hole next to your firing pin channel in your slide where the plastic LCI goes in first. Once in, we're almost done and you can start to install the slide cover plate. You can use the channel liner install tool to push down the firing pin assembly from the rear. A flathead screwdriver works good too but be careful not to scratch your slide if your tool slips.
You'll get it moved forward to where it touches the extractor depressor plunger. You'll need to use a punch, thin but strong blade knife or something to push down on that assembly while using your thumb to slide up the cover plate.
It'll take some time but after you assemble a few slides, you'll be able to complete a slide in less than ten minutes.
Your slide is ready for installation of your sights but also barrel and recoil spring assembly installation if you wanted to check function/fitment.