Improve the FAS 6004

[Rover]

You old curmudgeon, that's the best reply I've ever seen from you!

Tell it like it is!

[william]

You old curmudgeon, that's the best reply I've ever seen from you!

Tell it like it is!

Hey, who are you calling old?

[GoWyo!]

Ralph? Ralph Nader? I didn't know you were a shooter? Good reply. Methinkst you will get tired of tilting at windmills in the firearms and shooting industry's technical issues.

Maybe you would like to take on Detroit, Tokyo, Seol, and the UAW? ;)

Best,

Gary

[Chia]

And why the post? Simple, I long ago got sick and tired of companies who do their beta-testing with unsuspecting customers. When I - or anybody else - spends good money for a product he has every right to expect something that works. Unless it's clearly marked:

This POS may be nonfunctional out of the box and if so may require specialized tools and skills that you may or may not possess. Either way, it's not our fault.

They have seriously tried that in this country. Specifically, camera manufacturers made a camera with a bulb that exploded when flashing, blinding the user. They had a contract disclaiming responsibility for "any and all defects." Needless to say, they got sued, lost, and we now have a "warranty of general merchantability" requirement in this country. It is theoretically possible to disclaim by contract, but it doesn't really matter because you can't disclaim breach of contract or personal injury anyway. (Breach of contract in this case being that the gun are not usable for its ordinary use due to shitty manufacturing.)

The method of killing product lines is called a design defect case. If one person manages to prove that the design is defective in a single lawsuit, anyone can sue on the same principle and get their money (and attorney fees) back. It's fairly effective at preventing utter shit from getting into this country, but it's also why medical equipment is so expensive...

[GoWyo!]

Howdy,

For those of you that have done this, did you disassemble the pistol to get to the ported breach face or polish in place?

Thanks,

Gary

[slofyr]

...did you disassemble the pistol to get to the ported breach face or polish in place?..

You can polish the port face without disassembly. I fashioned a 'small' sanding block out of hardwood and went at it with a back-and-forth motion that followed the chamber arc. Start with 360 or 400 wet/dry paper lubed with Kroil or other light oil. When the surface is smooth, finish with 600.

[GoWyo!]

Just finished this mod, it was super easy since Slofyr did all of the research and leg work! Took me all of 30 minutes and although I haven't chronoed the pistol, it is now cutting nra 10 meter targets cleanly!

Thanks again.

[Troystat]

Neat write up. Just an FYI I tried this tune up on my new FAS 6004 and it appears to me that the dimensions of the barrel where the washer and o-ring fit in the write up has changed slightly and the washer and o-ring are just a bit too small. I am going to see if I can get some slightly larger washers from McMasters.

thanks

Troy

[Troystat]

I see the part where the original poster enlarged the shims with sand paper, sorry I missed that.

thanks

[Rover]

So no one has forwarded this to Chiappa?

[Troystat]

I tried this tuneup on my FAS 6004 that I bought a few months ago, the rubber washers from McMasteers did not fit but I did the tuneup and used the extra washer that came with the pistol and I think it helped a lot, when I shot it I got cleaner holes in the target and had to drop my rear sight by about 8 clicks because of the higher velocity. Thanks for the tip.

[clarky]

Modded pistol still running nicely but noticed slight flats appearing on the original O ring seal...about 3k rounds maybe..
FAS have changed that original spec cream col nylon seal and now going with the O ring ive been running since purchase..
So its good for about 3k rounds ...
I did add a small shim of 0.15mm to the head of the piston and picked up 25 fps in addition to the 20 fps i got from the breech sealing mods here...Knocking on tne door of 390 fps now ..
Apparently FAS are bringing out a higher power model called the SIG Supertarget ...which has a longer cylinder...hopefully it wont come with the std issues we had to iron out ...

[218bee]

Hi Clarky....By any chance do you remember the actual size of the breech oring? I just put a rebuild kit in a nice used 604 I just bought and there was no oring Identification in the kit. Just the spare orings. So far I love it. It can't outshoot my old FWB65, but it is close. With some more practice I feel I could match it.
Anyway thanks for any info on the oring size, as I wanna get a spare or two....and thanks for the write up. Very helpful...

218bee

[clarky]

Yeah sure bud ...you require a 7mm i/d x 1.5 thick nitrile ...
17mm x 2.5 for main piston seal ...

[218bee]

Clarky, or anyone that has worked on 604's..A question on my 604's barrel retention..I'm trying to get the front half inch of barrel (under the front sight dovetail) to be as tight as possible. Mine's an early, 4 digit serial gun, and I see from the factory, under the front sight, there is a small rectangular piece of spring steel, nicely recessed in the top frame, bent in a gradual "U" to impart downward pressure and help secure the front of the barrel, when assembled. Mine is about flat, with only a small amount of downward pressure on the barrel. Right now I can push up on the barrel, when the action is open, and feel a discenable amount of free play..not much, maybe a thousandth, but its there.
My question is, should I remove this flat spring, and re-bend it so it imparts much more downward pressure, as I'm guessing the factory intended, or should I take it a step further and drill a small hole through the top of the frame, right under the front sight screw and use the front sight screw as a much more solid way of removing all the barrel movement? Front sight assembly is one long dovetail, so it would be strong. Of course Id need a longer front sight screw. Just mulling this over..If anyone has any insight on this, it'd be much appreciated. Trying to tighten up groups..

Thanks

[clarky]

The barrel assembles into a location integral to the top barrel frame...the spring steel is only there to impart a bit of force to take out the tiny bit of slap....probably no greater than 0.1mm in reality. Sure you can add a bit of extra tension into that spring to kill any slight resonance but i cannot see it closing group size any..
I replaced that horrible Aluminium washer at the breech end...It doesnt really require the washer as it forces the barrel too hard against the transfer port area and is responsible for marking the transfer port bulkhead when the sealing washer isnt sufficiently thick enough ...but i suppose it looked like a good idea..
I use an O ring instead ..its got just enough force to keep it sealed but gives slightly to prevent too much force on the face of the bulkhead....It might also kill a tiny bit of resonance...I used a 9mm i/d stretch on...

Give the barrel a good clean...i got a load of black muck out of mine and flush the valve out with thin hydraulic oil..
Piston packing for 20 fps or so ...does improve card cutting..but a fair bit of work for not much gain....R10 pellets a must ..
Consistancy is 2fps shot to shot with one of these running right...it dont get better than that...but its like the thing requires a service from brand new...

[218bee]

Thanks again, Clarky... I have a new V10 (compact) pistol that just barely outshoots the FAS 604 and Im trying to wring all the accuracy I can out of the old 604, as I really like it better. The V10 has a rock-solid front barrel mounting setup that affords zero movement, via a large grub/set screw. I cant help but think the old 604 would benefit from such a setup. Might try hyper-bending the flat spring in the 604 and shoot some groups. Then go from there. Also running just a regular oring on the breech seal. Seems fine and I get close to 400fps with 7 grainers. I did remove the 604's barrel and tune up the muzzle and breech area, (chamfer & mirror polish) Here's a close up of the new V10's barrel retention setup. Don't know why FAS would not use this system...barrel is %100 motionless.

[clarky]

218bee ...it maybe that you are chasing something thats not required ...Im getting barely 0.1 mm clearance on the muzzle location which is the usual accepted clearance for precision locations on any guns and unlikely to realize anything in errors down range...
Ive found the real reason for the FAS not quite matching its competitors is owing to its speed...
Follow through etc become all the more critical when speeds are slow...lock time and speed to the target...Torn cards etc..
A gun must make 400 fps with wadcutters to be a realistic proposition IMO...
To do this with the FAS it requires major tuning to shift it from the 340 fps it is making...(V10 approx 370 fps)
Ive found the piston mod lifts into 385 fps territory and goes more accurate (the way to go) albeit with a bit of increased cocking effort ...
Correct breech set up following stoffers advice gives approx 15 fps..

[218bee]

Good stuff.....thanks again Clarky..

[clarky]

No problem bud...Ive come up with something new for this gun in terms of power but its kind of secret at the moment...You can PM for the detailsif you need to