FAS 602 Light Strikes

[JamesH]

Its been covered obliquely in another thread, but nevertheless:

Anyone know a reason why a FAS 602 should lightstrike?
With a brand new firing pin (tried two) it does it regularly, 1 in 5 roughly.

Rounds seem to chamber freely, the slide isn't floating around, its all spotlessly clean.
There is plenty of overtravel on the firing pin- its not short, mainspring seems OK, hammer spring seems OK - could be a little soft - do these weaken with age?
Happens with CCI and SK (never had a misfire with SK before).

I noticed the previous owner 'fine tuned' the firing pin by filing it to a rounded profile, ie looks rectangular from the front, round from the side so presumably he had trouble.
I assumed it was worn so changed it for good luck...

I never had this problem with my old FAS, new firing pins worked fine with any ammo.

Any ideas appreciated, also anyone know what standard headspace is?
I could put the old pin back in but it seems wise to fix the problem rather than fudge it.

[David Levene]

Anyone know a reason why a FAS 602 should lightstrike?
With a brand new firing pin (tried two) it does it regularly, 1 in 5 roughly.

The most common problemon the 602 is that the firing pin is hitting the case all the way out to the edge. You will appreciate that it is trying to compress a lot of brass at the edge. The fix that usually works is to file the firing pin so that it is striking inside the edge, thus only having to compress one thickness of the brass. Don't be tempted to sharpen the firing pin, I have never known it to be necessary.

If that doesn't work, and the firing pin is moving freely, then you will probably need to change the hammer spring (yes, they do weaken after 2-3 years). If you're going to do that then you should also change the pressure plate spring (the funny little "U" shaped one) as these weaken after 1-2 years. The most important thing to remember when working on the hammer box is not to even think about it unless you've got replacement spring pins. It is sometimes possible to re-use the old ones but it's a major pain in the butt.

BTW, some FAS firing pins were supplied with a rounded profile to concentrate the pressure inside the edge of the case.

[mister G]

And, if you get the terrors thinking about opening the hammer box, you can replace the entire hammer box assembly for around U$150. Neil Step at ISS in Texas still has two last time I checked.

[higginsdj]

I am no expert but had the same problem with the FAS 602 I have been shooting. Solution has been to use 'clean' ammo (ammo with no wax at all).

The consensus of opinion after lots of trial and error and inspections (not by me but more experienced folk) was that as the ammo was chambering a small amount of wax would build up at the breach preventing the brass from being fully seated (ie wax formed a little cushion). The Firing pin was therefore striking a movable object so was not able to deliver all it's energy appropriately.

Since that clean up - no misfires. We then just tried some waxy ammo (2 different brands - CCI and Target22) to see if it was just a fluke and both failed on the 2nd shot. Cleaned the breach and went back to the clean ammo and all is working perfectly again. The real clincher would be to use that CCI/Target22 ammo and clean them up just to rule out the ammo itself - but I can't undertake this test myself for at least another 2 months :)

Cheers

David

[David Levene]

The consensus of opinion after lots of trial and error and inspections (not by me but more experienced folk) was that as the ammo was chambering a small amount of wax would build up at the breach preventing the brass from being fully seated (ie wax formed a little cushion). The Firing pin was therefore striking a movable object so was not able to deliver all it's energy appropriately.

David, have you tried taking out the main slide spring. When it's not under pressure is it straight or has it developed a "wave". If the latter then you might want to think about replacing it. If it's over 2 years old then I would certainly replace it (I used to change mine annually).

Nobody ever said the 602 was low maintenance ;-)

[higginsdj]

The gunsmiths report was that all the parts were in perfectly good working order. They put 800 rounds through without a misfire. As I don't posess the pistol I only have access to it on the club Sunday shoots and then that is limited to the time it takes to complete the mornings event.
(Still 6 weeks to go before I can apply for my license - 6 mths passes by so slooooowwwwwwly)

BUT - that is excellent advice about checking springs. I always wondered how one could tell if they had gone 'off'.

Cheers

David

[JamesH]

Thanks for all the advice folks, a pile of spares is on order.

Curiously the only problem I ever had with my previous FAS was a broken firing pin, otherwise never needed a part and never malfunctioned with match ammo.

[higginsdj]

Hey James,

I'd be interested in staying in touch re progress with your FAS. I'm picking mine up second hand but can't take possession for a couple of months (but I get to use it every Sunday and am slowly learning the ins and outs)

Cheers

David

[JamesH]

Will let you know how it goes.

[JamesH]

Update:
Fitting a new hammer spring seems to have cured it, the old one had compressed permanently quite a bit.
Doctoring the firing pin went some way towards inproving it but wasn't quite enough.
I also squared up the barrel face, it was worn at the top, ie under the firing pin strike point due to crud getting trappped between slide and barrel - seems to be a feature of FAS 602s.

Apparently there are two types of hammer spring for the 602, straight and belled out in the middle - you need to know when ordering, maybe this was Fas' attempt to mitigate the problem.

Also the firing pin doesn't seem to project through all that far, any more problems and I might mill a smidgen out of the pocket in the rear of the slide.

[David Levene]

Also the firing pin doesn't seem to project through all that far, any more problems and I might mill a smidgen out of the pocket in the rear of the slide.

You might also want to check the cutout in the firing pin for the cross pin. It is not unheard of for that cutout to need relieving to allow full movement of the firing pin.

[JamesH]

You might also want to check the cutout in the firing pin for the cross pin. It is not unheard of for that cutout to need relieving to allow full movement of the firing pin.

Checked it, thanks, doesn't seem to be the problem.
Could be a little too much headspace also.

[LukeP]

I have the same problem: Fas 602 light strike.
Initially the pistol function like a dream, last training 300 rounds without any failure, the match soon after, less then 30 rounds and.. 1 bang 1 click... I have cleaned the pistol before match and also during match.
With various type of ammo (sk, lapua, rws, s&b) same light strike.

One piece at a time, I tried to change:
- hammer box screw.
- slide spring.
- firing pin and its own spring (firing pin hit the brass in the right way).
Chamber is clean.

This afternoon, as before one bang one click...

So i dismantled the hammer box (see below):
1. Hammer spring lenght is 31mm.
2. Pressure plate spring.
It's the last chance, tomorrow i'll go to buy and replace.

LukeP.

[JamesH]

I changed the recoil spring, hammer spring and eventually the barrel (very worn chamber) on mine.

It worked pretty well for a while, then played up and I noticed the firing pin was mushroomed over, seems the steel is rubbish, I'm not sure if they are original FAS or some batch made in Queensland.

I think the headspace on the slide is too high also, which isn't helping.

[David Levene]

It worked pretty well for a while, then played up and I noticed the firing pin was mushroomed over, seems the steel is rubbish, I'm not sure if they are original FAS or some batch made in Queensland.

Even the original FAS firing pins were sometimes (often) a bit dubious on quality (material and machining). That's why I always carried a spare that I had already fitted and knew worked.

[LukeP]

My local Fas distributor no more carry that old spring as spare, so he gave me the new one with a new rod (but the rod seems to be the same), is different inoutside diameter and end coils. Seems to strike better enough.

[JamesH]

I've heard about that alternative spring, might give it a try.

[LukeP]

Replacing literally all spring, and firing pin, don't fix the light strike. Today 3 out of 60 shots, in match.
I think about another pistol... :(

[David Levene]

Replacing literally all spring, and firing pin, don't fix the light strike. Today 3 out of 60 shots, in match.

Have you checked that the new firing pin is long enough (able to protride from the slide face by more than is needed to hit the cartridge properly) and the correct shape.

Are you certain that the inside corner of the case recess on the slide face is perfectly clean. If you just use a toothbrush then you will get a buil-up there which needs to be scraped out with a knife point or very small screwdriver.

Failing that, have you tried getting a good gunsmith, experienced with FAS, to have a look. I am certain there will be others but the only one I know of who is still working is Viktor Odermatt near Zurich. Do FAS still have any of their technicians.

[LukeP]

Thanks David,
yes i performed several times this check.
I also tested this brand of ammo: Sk, Lapua, Rws, Fiocchi, S&B, and always have a light strike every few rounds.

Last thing is removing estractor, it's the only thing i not tested.

I have also 4 magazine, and no difference among them.
I'll expect italian championship and put the pistol in Domino hands.