FAL firing out of battery! *Range report*

[JRottenjr]

Some of you MAY remember the trouble I was having with my rifle, I posted here about it several months ago. If not, short version: I could only get 3 mags through it and it would fail to feed. I put it away, bought a DSA STG58 and had a whole lotta fun. Back then I had called AZEX ARMS and spoke to the good Mr. Huffman and asked him if he would look at it, of course he said hell yes. Well Tuesday I finally made it to the other side of the world,( ie. Phoenix Metro) to have him take a look. Within about 60 seconds he had the bastid stripped and said: " it's got the wrong piston in it, look right here, it's been firing out of battery, yer lucky it didn't blow up in yer face". He checked head spacing, coated a screw black, and made a bumper to keep brass from maring the finish. After he Put it back together, I noticed a gas piston in my case and asked if he forgot to re-install it, He says he's got a bunch of 'em and he DIDN'T forget to install it, "that ones yers". So I ask him, "what do I owe ya for your time/parts" ? He says, "your money is no good here" . Thank you Derek ! Somehow, someway, I'll get you back, you won't see it coming. I never forget the good people I come across. AZEX ARMS is #1 in my book!








Hey all, well we made it out to the desert this AM, and all I can say things didn't go too well. The first mag went 5 rounds before I had a failure to fire. The primer had a light dimple, so I removed the mag, loaded the dimpled round in the chamber by hand, re-inserted the mag and it fired fine. The same mag full went ok for about 6 more rounds untill I had the second malfuntion, failure to fully send the round into battery, meaning the carrier didn't go all the way forward. Again I removed the mag, hand loaded the round, let the bolt/carrier go with the release, and it went home smooth as silk. This continued through out the day, sometimes I'd have no problems at all, and then I would, with the same types of malfuntion, non-fired rounds/failure to go into battery. This is starting to annoy me now, it would be real nice to get this weapon 100%. Anyone have any ideas on where to go on this one? On a side note, my buddy's son suggested he throw a plastic bottle of carbonated water into the air and have me try to pick it off. I did it, first shot! I figured it was a lucky shot and had him throw another............. missed it, and the other 3 too. Oh well, I ain't Henry Bowman.

[P806]

I agree, you don't forget.....the good guys.

[Pluribus]

I like a story that has a message of goodwill and end's happily

[dougjones31]

I have to ask....What kind of piston did you have in the gun? Wrong piston?

[ByronF]

Isn't an Izzy HB piston longer than the rest? Perhaps the HB piston protruded into the receiver far enough to prevent the carrier from going fully forward?

Byron

[JRottenjr]

Originally posted by ByronF
Isn't an Izzy HB piston longer than the rest? Perhaps the HB piston protruded into the receiver far enough to prevent the carrier from going fully forward?

Byron

I believe this to be the piston in question. It was protruding into the receiver about 3/16". It is for sale/trade.

[derek huffman, azexarms]

Thanks! Happy to help.

I have no idea how a DSA Izzy length piston when installed in a standard rifle would allow the weapn to work at all.

It scared me a bit just looking at it.

Hopefully, that'll fix his problems with functioning.

Once again, that's what I'm here for.

D.
AZEX

[Pa. Patriot]

I'm not sure that it was an unsafe condition.
Wrong - YES. But the gun was not firing "out of battery" the way I'm seeing it.
Let me explain:
The carrier has an amount of "jump" before it engages the bolt camming lug surface to lift it off the locking shoulder and out of battery.
So -
I believe the carrier has more forward travel after it seats the bolt on the LS than the longer izzy piston was holding it (carrier) back.
IOW It wasn't really firing*out of battery* in the sense that the bolt should have seated completely on the LS, it was just holding up the last 3/16" travel on the carrier... Bolt locked, carrier not exactly where it should be.
I believe the jump on the carrier is at least 3/16 before it engages the bolt lug cam surface on it's rearward travel.
Just a guess, I might check this later as it has peaked my curiosity...

ALSO: The design of the FAL will not allow out of battery firing *via a hammer strike*. If the carrier is back far enough that it is lifting the bolt off the LS it is also blocking the hammer travel from striking the firing pin.

The rear of the firing pin will not be protruding through the hole in the carrier (thus the hammer won't hit it)
The firing pin only protrudes through the hole AFTER the carrier passes the point at which the bolt is locked by camming it down on the LS (on the way forward) The carrier then moves forward the rest of the way which is like I said at least 3/16" IIRC...
Any clearer? or clear as mud?

[dougjones31]

I am with you Pa. Patriot!

Wrong...but not out of battery.

The longer piston shortened the unlock time and that could cause excessive gas pressure which could blow out a gas tube, but I would think that would be the biggest problem.

After looking at your problem description, I would say that the longer piston opening the breech earlier was causing the gun to heat up more. This heat was directly affecting the Carrier causing it to swell and cause more friction. The heat also could have affected the Mag springs and weakened them temporarily. Three mags with no problems and then problems on the 4th????? Yep, Sounds like some sort of funky heat/friction problem.

[JRottenjr]

Thank you all for you're replys. I'll be warming it up Sunday morning for the first time in 8 months. I hope it runs as expected. Thanks again Derek for your time.

[Pa. Patriot]

dougjones, interesting theory on the malfunction that ensued.
I suspect it may have also had something to do with inertia.
The carrier loosing that initial 3/16" of jump travel before engaging the caming surface of the bolt lug may have reduced the efffectiveness of the carrier/bolt recoil movement.... Just another theory.

[ratas calientes]

Originally posted by dougjones31
...
The longer piston shortened the unlock time and that could cause excessive gas pressure which could blow out a gas tube, but I would think that would be the biggest problem.

After looking at your problem description, I would say that the longer piston opening the breech earlier was causing the gun to heat up more. This heat was directly affecting the Carrier causing it to swell and cause more friction. The heat also could have affected the Mag springs and weakened them temporarily. Three mags with no problems and then problems on the 4th????? Yep, Sounds like some sort of funky heat/friction problem.

Boy, I don't know if I agree with this one. Interesting theory, anywho. (As an aside, since we can't argue about locking shoulder angles any more, I had to find something to get dougie all excited about. We need some more exciting debates here.)

First, the gun will not start to unlock until the bullet passes the gas port, when it is almost out of the barrel and has reached most if its final muzzle velocity. A significantly early unlock, if it happened, should reduce the pressure, but probably too late to effect what has already entered the gas tube, since the pressure in the gas tube is what pushed the bolt back in the first place. Also, wouldn't I get the same effect of early unlock if I close the gas regular and/or fire some hotter (performacne wise ) ammo?

Just some thoughts. What do you think doug?

JRottenjr - I hope she runs fine now.

Oh, and one more thing. I blame Derek partially for my addiction to Fals. I spotted some of his rifles for sale at a shop here in NM a few years ago, and they were nice. I never could afford one, though. But the rest is history. . .

[dougjones31]

You might have something there...If the gas pressure is less because of the early breech then it would compound the long piston/short stroke problem. I have to think that the early opening would decrease the gas pressure and add that to the less inertia......then you have a problem.

But this does not address the issue of the first 3 mags firing without a problem. If the problem was short gas or lost inertia then the gun would act up from the first shot. It had to be a heat/friction related related problem caused by the early breach. If , in fact , the piston was the problem???

[ratas calientes]

It will be interesting to see a range report, and see if it starts to malfunction after the first few mags. The rifle might still have another problem that has not been diagnosed yet.

[dougjones31]

Originally posted by ratas calientes
First, the gun will not start to unlock until the bullet passes the gas port, when it is almost out of the barrel and has reached most if its final muzzle velocity. A significantly early unlock, if it happened, should reduce the pressure, but probably too late to effect what has already entered the gas tube, since the pressure in the gas tube is what pushed the bolt back in the first place. Also, wouldn't I get the same effect of early unlock if I close the gas regular and/or fire some hotter (performacne wise ) ammo?

Well now......An early unlock will allow the gas pressure in the barrle to drop....the gas piston sees pressure from the barrel all the way up until the bullet leaves the barrel or the breech opens...whichever comes first....and that should be when the bullet leaves the barrel. But take into consideration the 3/16" less travel needed to unlock the bolt, and you do not know which is happening first. So everything said about this is just a hypothesis.

As for getting the same same affect by closing the gas regulator....I do not think so. Closing the gas regulator does not affect timing of the gas pulse/ Bolt unlock...it just reduces Gas presure or increases it. Think of the gas piston as the cam in an engine. It contols the timing of valve opening......the throttle position(Gas regulaator) or type of gas used(hot ammo) will not do that. Taller/shorter lobes and longer/shorter gas pistons would affect timing.

[Pa. Patriot]

Just a follow-up to my earlier comments.

I took some measurements, several rifles/makes.
During ejection, the carrier has a minimun of .250 travel rearward before it even hits the bolt lug cam.
The firing pin is blocked by the carrier at about the .175 mark (very close to 3/16")

Welp - back to work

[JRottenjr]

Originally posted by ratas calientes
It will be interesting to see a range report, and see if it starts to malfunction after the first few mags. The rifle might still have another problem that has not been diagnosed yet.

I'll have that range report Sunday. You may have something about, "another
problem". Hope yer wrong.

[ratas calientes]

Originally posted by JRottenjr
I'll have that range report Sunday. You may have something about, "another problem". Hope yer wrong.

So do I. I hope it runs 100%. Let us know.

[Court in Fl]

If the gas piston was protruding in to the receiver 3/16 of a inch I think
it was just a matter of time till something had to give, gas plug, gas block
or piston. As the full force of the carrier was bottoming out on the end of the piston and pushing it hard (forward) in the gas block.

Now the piston hits the gas plug any ways in normal functioning but not with the force of the bolt carrier on top of it.

Court in Fl.

[derek huffman, azexarms]

Bah! Sorry it didn't work...

Give me a call, I have to go to phx and pick up some AK wood from Barley Pop soon and I'll come get that rifle and attempt to figure out WTF is going on with it.

D.
AZEX

[JRottenjr]

Derek, PM sent.

[kotengu]

"throw a plastic bottle of carbonated water into the air and have me try to pick it off."

Not to be the nannypants of the operation, but what kind of a backstop did you have? A .308 will travel for miles and still do some damage.........

[Pa. Patriot]

Originally posted by Court in Fl
...
Now the piston hits the gas plug any ways in normal functioning but not with the force of the bolt carrier on top of it.

Good point.

[JRottenjr]

Originally posted by kotengu
"throw a plastic bottle of carbonated water into the air and have me try to pick it off."

Not to be the nannypants of the operation, but what kind of a backstop did you have? A .308 will travel for miles and still do some damage.........

There was a mountain, we were at the base of it. I was raised in a hunting family, and know to be aware of what's BEHIND my target. Thank you for your concern.

[kotengu]

Glad to hear it - like I said, no offense intended. You just never know who you're talking to.

[JRottenjr]

Originally posted by kotengu
Glad to hear it - like I said, no offense intended. You just never know who you're talking to.

I absolutely know that you don't know who is posting on these boards. No offense taken. Now, can someone direct me towards a solution to my dagnab problem with this infernal rifle?

[kotengu]

Well - it sounds like Derek's your best bet, but otherwise.....

What kind of ammo were you using? The failure to fire could just be attributed to hard primers (not uncommon in Port - it's happened to me a few times now). They almost always fire upon giving them a 2nd hit.

As for the failure to feed - there's a long list of things to check. First I'd check the mags - is it always the same mag(s) that gives you the sporadic problems (ie - 3 mags in, you grab the 4th, etc.)? Do the same mags always work in your other gun? After that - everything from too much lube in the recoil tube, to a leak somwhere in the gas system (maybe opening up as the barrel heats up, expanding the steel slightly). Is there evidence of leaking gas around the gasblock or gas tube/nut (ie - carbon buildup)?

There's a thread in FAQ that gives a pretty good checklist for problems like this - search FTF FTE, etc.

Good luck, and keep us updated!

[JRottenjr]

Originally posted by kotengu
Well - it sounds like Derek's your best bet, but otherwise.....

What kind of ammo were you using? The failure to fire could just be attributed to hard primers (not uncommon in Port - it's happened to me a few times now). They almost always fire upon giving them a 2nd hit.

As for the failure to feed - there's a long list of things to check. First I'd check the mags - is it always the same mag(s) that gives you the sporadic problems (ie - 3 mags in, you grab the 4th, etc.)? Do the same mags always work in your other gun? After that - everything from too much lube in the recoil tube, to a leak somwhere in the gas system (maybe opening up as the barrel heats up, expanding the steel slightly). Is there evidence of leaking gas around the gasblock or gas tube/nut (ie - carbon buildup)?

There's a thread in FAQ that gives a pretty good checklist for problems like this - search FTF FTE, etc.

Good luck, and keep us updated!

Yes, I am using port, it runs through my DSA STG58 with no problem. I have 25 mags, was trying different ones each time. They all work fine in the DSA. I DID find that the gas tube was a little loose when I was cleaning the rifle, less than 1/16 of a turn to tighten. There IS some carbon build-up at the nut. Could the recoil spring be "weak", not bringing the carrier back hard enough? Also I noticed the rounds that would not feed were scratched pretty bad. FWIW.

[kotengu]

"rounds that would not feed were scratched pretty bad. "

Ahh - now we may be getting somewhere. It's common for the underside of the rails of some receivers to have burrs on them. Some 400grit sanpaper to relieve the sharp corners on the underside of the rails (where the rounds drag accross) would be a good place to start.

You may try swapping recoil springs with your DSA (or complete lowers, for that matter) and see if that makes a difference - if it does, you know which part to replace. Make sure you have minimum lube in the recoil tube, or you'll create a hydraulic lock that will inhibit good movement.

Swapping lowers (or just hammer springs maybe) might tell you whether your primer dimpling problem is due to the ammo or the gun. I've had it run fine in one one gun, but then fail to fire from time to time in another, no matter how many parts I replaced. It drove me crazy for a long time, but in only happens with Port.

Also - it wouldn't hurt to start putting a small piece of masking tape on the mags that you're using when you have troubles. It doesn't sound like the mags are at fault here, but it would eliminate a variable.

[ratas calientes]

Check the info in this thread:

http://www.falfiles.com/forums/showt...iver+AND+rails

[JRottenjr]

Originally posted by ratas calientes
Check the info in this thread:

http://www.falfiles.com/forums/showt...iver+AND+rails

Thanks for the thread, sounds almost exactly like the problems I'm having.
Also, thanks to all others who have given their input on this. I'll try 'em out and if I FAiL, off to AZEX it goes. Damn! I've had this rifle over a year, and still can't get it to operate 100%, If it weren't such a beautiful weapon I'd have traded it off long ago for a few SAR1's.