Improve the FAS 6004

[slofyr]

...I would just put a smear of pellgun oil on the O ring to help lube it as it will not block the transfer port.

Try Sil-Glyde https://tinyurl.com/yaysoacb . Put a 'light' smear on a finger pad and then just tap it on the o-ring. Sil-Glyde has better film strength and will last longer than the oil.

[clarky]

Nice one Slof ..I will try it. How is your 6004 going..

[slofyr]

10 after 10 after 10.... it's sorta boring.

[clarky]

Agreed, once set up correctly it is easily the best Air pistol of this type. Its a shame Chiappa did not get it fully sorted out of the box, before its release. Unfortunately its rep has been badly affected by not doing so...
Sweet spotting the trigger took me a full morning messing about but trounces everything up to a 1k PCP.
Sorting the sealing sees 400 fps with sub 5 fps variation..

[cgeiser]

Clarky - I may be ordering an FAS 6005 soon. Would you be able share the part number of Quad seal that worked for the breach and for the piston?
Thank you!

[clarky]

7mm I/D breech seal. 17mm I/D Piston seal. From what i have found, cross section is fairly standard unless a special.

[mister G]

A suggestion ... I've stopped using pretty much any kind of petroleum-based oil/lubricant on my O-rings and substituted silicone lube. Seen too much degradation of O-ring rubber.

[Gwhite]

The generally recommended lube for O-rings these days is Superlube, which is silicone based. It's become pretty popular, and it available in a lot of automotive & hardware stores in the USA. The 1/2 oz. tube will last a lifetime:



For O-rings, all you want is a very thin layer of lube. A lot of people make the mistake of thinking that if a little is good, a lot is magically better. All that does is gunk things up and attract dirt, which O-rings hate.

A lot of older pure silicone greases aren't actually very good for metal to metal applications. SuperLube is different (maybe the added Teflon) and is recommended for things like the threads on PCP cylinders.

[mister G]

I agree 100% on Superlube.

I rebuilt my FAS 604 (It was a Domino 404 when I bought it long ago!) and used silicone-based lube with excellent results/

[clarky]

The Superlube is very good stuff for O rings and should be fine.
I just went the route of Pellgun as i was a touch concerned with galling risks when Silicone comes into metal on metal contact.
You can also use a drop of the Pellgun down inside the transfer port to lube the valve O rings and prevent sticking of the valve. You cannot use the grease down through there but each to their own.

For anyone performing these mods to their 6004, here are the expected velocity figures based on the last one I did.
Which i tested at each stage of the tune.
Using R10 Pellets.
Out of box with a few clearing shots. 327 FPS (Avg) Extreme spread 15 FPS.
Valve and piston flushed of grease and relubed. 335 FPS Extreme spread 14 FPS
Barrel entry re-machined with Countersink tool and polished. 355 FPS Extreme spread 14 FPS
Barrel groove seal replaced with Quad Seal, Or original O ring with an added backing washer 369 FPS Extreme spread 5 FPS
Note.. The extreme spread remained largely unaffected by the cleaning out and refinishing of the barrel but went single figure when sealing was corrected. Its suggesting all the low velocity and inconsistency is coming from this sealing issue and the rest of the work just me chasing perfection.

Finally, 0.4 mm piston pack gave an additional 27 FPS Extreme spread 6 FPS.
An additional 7 FPS can be had from using Finale match lights but not stocked in my local store last time I was in.

[clarky]

Finally, ending my work...at least in regard of the FAS 6004, I achieved 414 fps Avg with a 5 FPS variation on Finale ..
Many might say what a waste of time, especially if comparing to the modern PCP pistol running low 500s but trust me this was huge for me, coming from 327 fps. I honestly never thought i would make 380 fps at the outset of the work and it does mean a reasonable performance from a self contained gun, with no bottles or power curves to worry about.
It means clean cut cards and even manages to put down knockdowns at 15 mtrs and that is about as accurate as i can shoot a pistol off hand.
It means that this best looking of pistols can now marginally out power stock HW40/75 and P17 variants.
However, after finally reaming the transfer port to pick up 10fps, I realise there is no more to be had in this gun and I move onto my next project..

[Chris K]

Clarky - Can you explain more about the Quad seals. Can't find them on RS. Are they the ones with a sort of X section? I've been using a square breech seal turned from urethane but I would love to try the Quad type on the piston.

[william]

This is the thread that wouldn't die. I never would have guessed there were so many people who really wanted to buy an air pistol in kit form - missing some the necessary parts in the box.

"Sweet spotting the trigger took me a full morning messing about but trounces everything up to a 1k PCP." What exactly does "trounces" mean?
_Uniformity of velocity? I've had multiple pistols that were under ±3fps with the right pellets.
_Group size? Too many thousands of words have bees shared in these forums about the importance of the pellet, including batch-testing to match the specific barrel.
_Or in the end is it: "After all the time and effort I put into this thing, I need to show it was worth it."

[clarky]

Chris...Quad seals and X seals are one and the same thing.
You can purchase individually the sizes mentioned in this thread from a Hydraulics cat on line but I went with a the selection Kit available through RS components because i service lots of guns for people...not just the FAS..

William..I do not understand the drive of your post but Trounces means betters, or beats other models of this type.
There are better choices but not at this price point if you are prepared to meddle a bit.
If you do not have the required skills or patience...i suggest buying another model but good luck with that one at the price point.

The 46M probably is a better option ...if you can find one but I just could not get on with the damn contraption ..

[Chris K]

Thanks Clarky, now I know exactly what they are I can find them from various seal suppliers online. I feel more messing and improving coming on!

[Gwhite]

7mm I/D breech seal. 17mm I/D Piston seal. From what i have found, cross section is fairly standard unless a special.

I'm intrigued by the idea of the X-seals. I did the mod with just an O-ring & a spacer a while back & that has worked OK. I looked at McMaster Carr, the the two 7mm I/D X seals they carry are 1.5 mm (#1200N119) & 2 mm (#1200N155)cross-section. I'm guessing you want the 2 mm version. Is that correct?

Thanks!

[clarky]

The FAS O ring is a strange size...being 6.8mm inside diameter x 1.78mm thickness but selecting an 010 size works best ..
The 2mm cross section being a tight squeeze will go in.
I polished 0.2mm out of the outer diameter of the groove on mine for a nice slide on std 2mm thick seals.

[huckleberg]

The FAS O ring is a strange size...being 6.8mm inside diameter x 1.78mm thickness but selecting an 010 size works best ..
The 2mm cross section being a tight squeeze will go in.
I polished 0.2mm out of the outer diameter of the groove on mine for a nice slide on std 2mm thick seals.

Don't get 10x7x1.5mm O-Rings, they are definitely the wrong size, I spent a bunch of money different kinds and now they are going up on eBay.

I kinda got mine to work using two layers of shims and the ring disk thingy that OP mentioned.

[huckleberg]

This is the thread that wouldn't die. I never would have guessed there were so many people who really wanted to buy an air pistol in kit form - missing some the necessary parts in the box.

"Sweet spotting the trigger took me a full morning messing about but trounces everything up to a 1k PCP." What exactly does "trounces" mean?
_Uniformity of velocity? I've had multiple pistols that were under ±3fps with the right pellets.
_Group size? Too many thousands of words have bees shared in these forums about the importance of the pellet, including batch-testing to match the specific barrel.
_Or in the end is it: "After all the time and effort I put into this thing, I need to show it was worth it."

No need to be snarky to clarky, but ultimately you are correct in my opinion ... Chiappa should recall the barrels and replace them (free of charge) with a more sensible breech end that fits a standard seal without needing repeated maintenance. That or someone could probably engineer some sort of cap that fits over the breech and holds a thicker O-Ring, and sell the as an aftermarket part.

Every time I shoot a bad group with my FAS I have to wonder if it's me or if I need to redo the breech seal. Usually it's me ... but I've re-seated the barrel and replaced the seal repeatedly and had tighter groups the next few hundred pellets. Repeat ad nausea.

I cannot recommend the FAS due to this repeated problem.

[clarky]

If you PM Slofyr ...who started this post, or ask me, all i can say is we both produce boring 10 upon 10.

You are correct Huck that the seal groove requires sorting so it fits std 2mm cross section O rings.
This would allow plenty sitting proud to not need a packing washer. I took a skim out of the O/D of the groove on the lathe to get it right...but heaven alone knows why they dropped that original seal used on the 406 version, which worked perfectly for years.
Slofyr seems to have cured his by going with the Mcmaster seal...Be good if he could chime in here ..but I am aware rubber seals like that can turn up varying in size.
He must have got lucky.
Thanks for the support Huck on the previous post but i just ignore crap like that. I was just trying to help shooting fellows having issues with their FAS, not blow smoke up my ass for the work I pretty much copied from Slofyr....all the credit goes to him.