FAS604 Repair

[fc60]

Greetings,

I have disassembled my FAS604 into the basic components.

Now I am stuck.

How do I remove the plunger in the photo to replace the O-Rings?

Cheers,

Dave

[marky-d]

Pull hard.
Mine was stuck pretty badly -- the o-ring had turned to paste. I don't remember what I finally used to get it out; I think I may have used a piece of wood or brass to wedge under the 'button', then levered it against the body.

marky-d

[fc60]

Greetings marky-d,

Many thanks!!!

I shall go and exert more force.

Cheers,

Dave

[fc60]

Greetings,

I am at the O-Ring point.

Looking at Buna-N (70A) material as it is oil resistant. (I ordered a tube of Crosman PellGun Oil.)

Interesting as the O-Rings I removed (Piston and valve) were Red suggesting they were Silicon.

When I put the beastie back together, what FPS via the chronograph should I get with 7 grain pellets to assure myself I did a good job of assembly?

Cheers,

Dave

[Rover]

Not too long ago, there was a thread on rebuild for max velocity. Go hunting!

One thing I did notice was that you could get a velocity increase of around 20 fps by using RWS Meisterkugeln Blue (pistol) pellets.

[Gwhite]

<snip>
Interesting as the O-Rings I removed (Piston and valve) were Red suggesting they were Silicon.
<snip>

Unfortunately, O-ring colors aren't standardized, and are often meaningless.

https://www.globaloring.com/oring-colors/

"It is never safe to assume an o-ring is a specific material based on the color alone." They are also happy to make custom O-rings in any color you want...

I think the colors used in the US are also different from what the Europeans use. Walther used to use green polyurethane O-rings in their CO2 pistols, but I think the green O-rings Steyr uses now may be Viton.

Nitrile should be fine, but you may find that a harder (like D90) O-ring holds up better in some applications than the standard D70. The FAS isn't a high pressure application, and the D70 is probably fine.

[brent375hh]

Not too long ago, there was a thread on rebuild for max velocity. Go hunting!

One thing I did notice was that you could get a velocity increase of around 20 fps by using RWS Meisterkugeln Blue (pistol) pellets.

Where can one purchase these blue pellets?