FAS604 Repair

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fc60
Posts: 748
Joined: Fri Nov 25, 2005 11:46 am
Location: Western Washington State, USA 98385

FAS604 Repair

Post by 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
IMG_20231105_154829953_small.jpg
marky-d
Posts: 231
Joined: Sun Oct 08, 2017 10:22 pm

Re: FAS604 Repair

Post by 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
Posts: 748
Joined: Fri Nov 25, 2005 11:46 am
Location: Western Washington State, USA 98385

Re: FAS604 Repair

Post by fc60 »

Greetings marky-d,

Many thanks!!!

I shall go and exert more force.

Cheers,

Dave
fc60
Posts: 748
Joined: Fri Nov 25, 2005 11:46 am
Location: Western Washington State, USA 98385

Re: FAS604 Repair

Post by 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
Posts: 7045
Joined: Sat Nov 15, 2008 4:20 pm
Location: Idaho panhandle

Re: FAS604 Repair

Post by 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
Posts: 3398
Joined: Sat Sep 04, 2004 6:04 pm
Location: Massachusetts

Re: FAS604 Repair

Post by Gwhite »

fc60 wrote: Mon Nov 06, 2023 9:07 pm <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
Posts: 740
Joined: Wed Apr 17, 2013 8:04 am
Location: Minneapolis

Re: FAS604 Repair

Post by brent375hh »

Rover wrote: Tue Nov 07, 2023 8:04 am 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?
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