TargetTalk

Hi everyone - I just picked up a well-used FAS604 which has no compression. I want to go ahead and replace the seals, but can't find a reference on-line to tell me what size they are. Does anyone know?

Thanks in advance.

TomAmlie

All NBR 70 shore A

Valve inner seal 4mmi/d x 2mm

Valve outer seals 7mmi/d x 1.5mm

Breech seal 7mmi/d x 1.5mm

Breech Block 17mmi/d x 2.5mm

Piston seal 17mmi/d x 2.5mm

I have the Breech block/piston seals (same size) if you are stuck I can send them to you (I'm in the UK). I may have some of the others also.

Many thanks, Silvershooter.

I've been looking a bit on-line, and I'm wondering what the best material is for the seals. Viton? Buna? Silicon? I hate to admit it, but I don't know what "NBR 70 shore A" means.

Hi TomAmlie
The ones I have are Nitrile. I think NBR 70 Shore refers to hardness or density.

NBR = nitrile rubber (Buna-N)
70 Shore A = 'hardness' (about the hardness of the sidewalls of a car tire)

I use those sides :

17,13 2,62
6,75 1,78
3,69 1,78

They fit well !

BenHHH wrote:I use those sizes :

17,13 2,62

6,75 1,78

3,69 1,78

They fit well !

Sorry to revive old post but I agree with these sizes . They are otherwise known by British Standard sizes
BS115
BS610
BS007 respectively

I found the metric 1.5 and 2.5 sections not enough to seal well particularly on the piston.
NBR Nitrile is fine. Avoid Silicone like the plague. I bought a set of red ones and they lasted 10 shots.

For fitting see https://www.youtube.com/watch?v=q3a1Ma2fcg4

Greetings,

A while back, I received a seal kit from FAS. The larger 0-ring was reddish in color. I cannot recall the color of the smaller ones.

Point being, the larger one "seemed" to be of a different material.

Try contacting FAS via email. They "might" be of some help.

Cheers,

Dave

Buying O-rings can be a pain in the neck. Step 1 is to get the size right. Even that can be tricky, because the "size" often doesn't match the actual dimensions.

Step 2 is to pick a good material. Most materials will work well with air, but urethane is best if you are shooting with CO2. If the seal is used in a dynamic (rubbing or sliding) vs static situation, some material are more abrasion & tear resistant than others.

Last item is the hardness, specified as a "Durometer" rating. Typical Buna-n Nitrile O-rings you might find at the hardware store are usually Durometer A70. At very high pressures (like PCP fill seals & adapters), you are often better off with a harder O-ring, like A90.

There is a good chart that discusses O-ring properties here:

http://www.mcmaster.com/#o-rings/=141dqwa Click on "About O-Rings" at the top of the page.

for the FAS 604 I would say that hardness 70 is just fine. the pressures are nowhere near PCP cylinder pressures.
I have also tried "upgraded material" piston O Rings like Fluro brown rings and they last a few hundred shots. Nitrile are very long lasting in this pistol, and like 20 pence/cents each.

fc60 wrote: ..Try contacting FAS via email. They "might" be of some help.
Cheers,
Dave

FAS no longer exist. the FAS 6004 replacement is made by Chiappa who do not answer emails it seems.

TenMetrePeter wrote:...the pressures are nowhere near PCP cylinder pressures..

Duh, it's an SSP.

TenMetrePeter wrote:....the Ghastly FAS 6004 replacement is made by Chiappa....

Ghastly? That's a bit of a generalization which doesn't do much for your credibility. I agree that Chiappa is not the best company but not all 6004's missed the second inspection.

.

Play nice, friends.

I know this is an old thread, but considering I just had to rebuild one of these, I thought I'd make an additional note that may help others:

In terms of 'standard' US SAE o-ring dash numbers, you will need
2pc -115 (for the piston and breech block)
2pc -010 (for the breech face and valve assy)
2pc -007 (the other two in the valve assy)

Note the -115 is the same as the BS115 and -007 is the same as the BS007 noted above. The published dimensions of the -010 is slightly different from the BS610, but it's very close.

marky-d