CROSMAN T4 CO2 pistol
Here is the strip procedure for our Crosman T4 CO2 pistol. If you doubt your ability or perseverance to do the strip and then the rebuild (part 2) do not attempt it. It is not easy. But it can be done.

Note: This is not a difficult pistol to strip but the rebuild is not easy due to having to locate various components and keep them located while the top slide is pushed into engagement on the lower frame. Some special tools are also needed: if you intend to service the CO2 capsule inlet you will need a broad blade (approx ½”) to unscrew the inlet retaining nut. If you need to service the valve mechanism you will need a pair of circlip pliers with fine ends to remove an internal circlip. The rest of the pistol strips quite easily with a few standard tools.
It helps to download the exploded diagram of the pistol from the Crosman web site. Numbers presented in this guide refer to component numbers on that diagram.
Once the frame has been separated into main body and action, the rest of the pistol is built on modules.
Our pistol, bought at auction, was terrible. To start with the CO2 escaped when we loaded a capsule. I corrected this by adding some Pellgun oil to the seal. It would then not eject a pellet out of the magazine but just went a wimpish ‘phut’. It took a few strips to narrow down the reason ... basically it was either no gas getting into the valve or non getting out. I eliminated the first, which left the latter. It turned out to be the safety link, part 33 that had been fitted incorrectly ... see rebuild.

Strip: Remove the CO2 capsule carrier. Looking at the pistol, note 3 pins through the action. 2 pins through the hand grip (15 + 15) and a slightly thinner pin (18) forward of the trigger guard. There is no need to remove pin 18. Removal of the rear pin 15 allows the grip (14) and piercing lever mechanism to be removed. If you intend to get at the trigger unit and valve system, remove the pin (15) near trigger guard.
There is no need to remove the rear sight.
The top slide is sprung onto the main body and is held by shallow ridges on the slide. There is one ridge each side on the trigger block and a further one each side just forward of the trigger guard as part of the main body. You need to spring the sides of the slide from these ridges. I used a broad blade screwdriver to do this but take care that you do not damage the sides of the slide or the main body. When you have one side free, spring the other side free but keep the slide and main body held together. There are no small components to ping away but be prepared for the next step which is actual separation of the slide from the body.
With the trigger block exposed, hold it in position while you lift the slide and move it forward towards the muzzle. Try to keep the shroud assembly (part 2 which contains the barrel and indexing system) inside the slide at this point. As you lift this off the main body you will release a spring that fits over the guide rod beneath the barrel from its location in the main body. It will not fly away and should simply come away sitting on the rod.
If you manage to leave part 2 inside the action but release it from the slide, do not worry, but in doing so you will release part 4, the shroud release spring on the barrel from its housing and will need to reposition it during the rebuild.
You may now have the top slide plus shroud assembly and the main body with the trigger block assembly inside.
List the trigger assembly away, noting that the shroud release lever ((21) comes with it. This may just fall off its locating peg but do not worry.

Servicing the valve: Look at the trigger housing (11) and note a screw (10) holding the lh plate to the rh plate. Remove this screw and gently lift the lh plate away. It helps to keep a finger on the trigger to keep the trigger against the rh plate while you do this. With the lh plate removed you can see all the components ... trigger (35), trigger spring (34), hammer with spring (32), the valve assembly (30) and a component called the safety link (33) which is a piece of bent rod approx 2mm diameter that locates through holes attached to a bar on the trigger and sits between the valve pin and the hammer.
The valve unit body just lifts away from its location on the rh plate. To access the capsule seal, undo the nut using the broad blade and remove, in order, the seal (30B), the piercing pin (30C) and the filter/screen (30D). Note that if all you need to do is replace any of these components, this can be done without the full pistol strip as they are accessible through the pistol grip once the capsule carrier is removed (rear pin 15).
To access the exhaust valve, remove the circlip (30J) and let the valve seal and valve stem come away. Releasing the circlip allows these parts to come out under slight spring pressure. Remove spring, a steel washer and a seal (30F). An O ring (30K) will most likely stay inside the valve body. Replace parts as necessary.
At the front of the valve body is the part that transfers gas to the pellet ... a black push on cap with a sprung transfer port. If needed, the cap just pulls off to release a small spring and the transfer port tube.

This is really as far as you need to go with a normal service strip. Other components, shroud assembly and CO2 capsule carrier can be stripped if needed but I had no need to do this.

Rebuild follows
Cheers, Phil