FAS AP604 Lubrciation question

[silvershooter]

A seal has gone in my FAS, I have a replacement set of silicone seals, Q what lubricants should I use and what to avoid, advice appreciated.

[wonky donky]

A seal has gone in my FAS, I have a replacement set of silicone seals, Q what lubricants should I use and what to avoid, advice appreciated.

Are you quite sure your seals are SILICON? I've never known Silicon seals fitted to any airgun as they aren't usually up to the job, but there's always a first

Replacement seals are usually NBR or Pur (polyurethane)

Just put a little silicon "Oil" between your fingers & rub each seal with it, the seal should only glisten not be wet if you see what I mean, that's enough! Too much lubricant can stop the valve opening properly & will cause inconsistency between shots.
Metal to metal stressed or moving parts can have a small amount of moly grease on them & the felt on the piston (if fitted) can have a tiny amount of light machine oil on it.

The key is....... little is more!

[silvershooter]

Are you quite sure your seals are SILICON? I've never known Silicon seals fitted to any airgun as they aren't usually up to the job, but there's always a first

Thanks wonky donky, I found them on 'bay http://cgi./FAS-AP604-Air-Pistol-Rep...94606904088095

The link does not seem to work but a search for FAS AP604 on bay will find the part.

[wonky donky]

Thanks wonky donky, I found them on 'bay http://cgi./FAS-AP604-Air-Pistol-Rep...94606904088095

The link does not seem to work but a search for FAS AP604 on bay will find the part.

I've ordered 2 sets to see what they are like.


Originally these pistols were fitted with NBR "O" rings of which I have about 30 sets in my workshop. If these "O" rings off the bay do turn out to be Silicon I will test a set but will not put them in someone else's pistol until I have proved them myself over say 12 or 18 months......but that's just me.

[silvershooter]

I came accross this thread today , the poster has given a link to a manufacturer of Nitrile and Vitron O rings : http://www.airgunbbs.com/showthread....t-o-quot-rings

What is NBR ?

(So far the silicone seals fine, after about 50 pellets.)

[wonky donky]

I came accross this thread today , the poster has given a link to a manufacturer of Nitrile and Vitron O rings : http://www.airgunbbs.com/showthread....t-o-quot-rings

What is NBR ?

(So far the silicone seals fine, after about 50 pellets.)

NBR is Nitrile Buna-N.

I am really interested to see how Silicon does stand up. It has poor tensile strength, tear resistance & abrasion resistance.

Viton will do the job as will EPDM but the physical properties & cost make NBR more attractive to manufacturers, as does Pur in certain applications.

[silvershooter]

When I bought the FAS the O rings had just been replaced, after about 6 weeks and 3 - 4 tins the piston seal has lost compression. Now there is definitely more power (with these silicone O rings) compared to when I first bought it.

[wonky donky]

I've just resealed a 604 & found the shoulder on the valve that holds the top seal was rounded off slightly. This caused the "O" ring to jump off the valve when firing, thus stopping the pistol from compressing the air.

It was easy to rectify with a little basic machining but I'm beginning to wonder if this is problem that arises during the life time of the 604, as this is the third one I've repaired with the same problem in the last 18 months or so.

One problem with the FAS 604 I have found & the late Gerald Cardew used to complain about, some pistols would not seal if the correct size "O" rings were fitted, so making it necessary to fit either under or oversize "O" rings which ever the case may be.

[silvershooter]

One problem with the FAS 604 I have found & the late Gerald Cardew used to complain about, some pistols would not seal if the correct size "O" rings were fitted, so making it necessary to fit either under or oversize "O" rings which ever the case may be.

I am going to order some seals from the Altec web company. What is the correct size for the piston and breech seals ? the ones I have taken off seem to be ID 18.00mm and cross section 2mm, though some must have been worn away as the piston moved very easily in the cylinder.
Does dry firing damage these pistols ?

[silvershooter]

It's funny the way Italian's build things. I have had an Italian motorcylce (Motoguzzi) and have a Gaggia coffee machine and you see this quirky way of building things , basically good ideas but they tend to fall down in some way.

[wonky donky]

It's funny the way Italian's build things. I have had an Italian motorcylce (Motoguzzi) and have a Gaggia coffee machine and you see this quirky way of building things , basically good ideas but they tend to fall down in some way.

You have a PM

[silvershooter]

You have a PM

Thanks WD, have replied with a PM but I don't think they are being sent.