TargetTalk

My FAS 604 pistol has developed a lack of compression on cocking (together with a faint hiss on closing the gun). Out of its box, the first shot was fine, but after that the gun closes with no effort and you just get the click of the trigger releasing (and no pellet out of the other end!).

I'm assuming that this is either a piston seal passing or a stuck valve. However I've not had it to bits - has anyone taken one of these apart and know of any potential pitfalls before I leap in with tools?

Any advice greatly appreciated.

cheers

Matt

Here is a link to a diagram:

http://missingg.com/tenp/fas604ex.htm

If Scott doesn't have the parts, Neal Stepp at ISS may still have some for the 604

toznerd

Here's another link to Domino's parts page for the 604:

http://www.fasdomino.com/sito/eng/pg2/f-start.htm

It sounds like either the little seals on the valve (#220 & #219) are bad or the valve is stuck open. It looks like you can't replace the valve spring, but rather the whole assembly (#212 for about 18 euros).

And, I just noticed that you are in Europe, so you'll have to find parts locally.

toznerd

Matt

If you need a seal set then give Diverse Trading a ring. He advertises in The Rifleman.

Thanks guys,
I've managed to locate a shop who has seal kits - just got to work out how to take it apart now!

cheers
Matt

I got the O-ring kit from Canada some years back and have stripped my Domino 604 many, many times. It isn't difficult if you proceed slowly and study the parts diagram.

You might find that replacing just the small O-rings will cure the problem, so initially stay away from the big piston.

Like me, I think you'll find that the small O-rings have turned to wax due to exposure to petroleum-based lubricants. Use silicone grease/oil from now on.

Thanks for the advice guys.

I've got it all disassembled now, just waiting for my seal kit to arrive.

All the o-rings had deteriorated - most of the valve assembly seals had hardened and a couple split as I was removing them, but the big problem was obvious as soon as I got the piston out of the cylinder:





Don't think there's any doubt why it had no compression!

The green mess from the disintegrated piston head o-ring had made it's way into the valve assembly so everything went into my little ultrasound bath.

Just waiting for the new seals, then it's re-build time!

thanks for all the advice

best
Matt

MattW wrote: Any advice greatly appreciated.

Try info@dominoguns.com

mister G wrote:I got the O-ring kit from Canada some years back and have stripped my Domino 604 many, many times....Like me, I think you'll find that the small O-rings have turned to wax due to exposure to petroleum-based lubricants. Use silicone grease/oil from now on.

Matt,

My experience with the FAS O-rings available in the US is a reflection of the above quote. These O-rings go bad quickly when exposed to petroleum-based lubricants....and when exposed to silicone lubricants....and when just sitting on the shelf. IMHO they are just poor quality, and should be substituted with high quality alternatives. Then you won't have to repeat the rebuild "many, many times."

HTH,
FredB