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Old November 01, 2017, 17:31   #1
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Argentine gas system problem

I seem to be having the complete opposite problem with my FAL compared to what others have. I can't adjust the gas regulator to the point where the bolt won't lock open, ever. I'm shooting LC ball ammo and no matter how far open I have the gas, the bolt locks back after every single loaded shot. What am I doing wrong?

I've replaced the recoil springs with brand new FN parts, and am going to replace the gas piston spring with a new one. I don't believe any of the springs should have to be replaced, because the rifle has been fired less than 100 rds since it was new.

Any ideas?
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Old November 01, 2017, 18:03   #2
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Pin on the BHO too long catching the cartridge rims ???
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Old November 01, 2017, 18:12   #3
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Nothing to do with the gas. Failure to lock open may be too little gas, but locking open with a round remaining in the mag, is your BHO.

I suspect the plunger inside it is jammed down - no spring pressure. So it pops up under recoil, rather than from mag follower contact.

Take it out, flip it upside down, and rap it hard and repeatedly on a hard surface. Kinetic energy should move the plunger. Once you have it up, blow the spring with compressed air. Then take a small punch through the slot and push the plunger down. If it doesn't come back up on it's own, repeat the rapping.

This is something I have to do all the time after refinishing, as I do not disassemble them first (that causes more problems than working the spring free from blasting dust afterwards).
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Old November 01, 2017, 18:14   #4
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On a side note, most tall block Argy guns will have a type A regulator, which does not adjust from 1-7 only, as a type B or C. It can be turned past 7 and back to 1, as the ellipse is much more shallow.
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Old November 01, 2017, 19:03   #5
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Nothing to do with the gas. Failure to lock open may be too little gas, but locking open with a round remaining in the mag, is your BHO.

I suspect the plunger inside it is jammed down - no spring pressure. So it pops up under recoil, rather than from mag follower contact.

Take it out, flip it upside down, and rap it hard and repeatedly on a hard surface. Kinetic energy should move the plunger. Once you have it up, blow the spring with compressed air. Then take a small punch through the slot and push the plunger down. If it doesn't come back up on it's own, repeat the rapping.
Just removed the bho and the plunger didn't appear to be stuck, but it did seem to be "sticky". Cleaned it well and relubed. Will see what happens probably Friday.

The spring that operated the plunger is really light, pressurewise. Could that be a problem?
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Old November 01, 2017, 19:25   #6
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could be the spring is damaged. Upside down will it pop down (up) under spring pressure?
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Old November 01, 2017, 19:31   #7
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Yep, it pops right back up, but not with much force.
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Old November 01, 2017, 19:49   #8
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Just thinkin', for the bolt carrier to lock back, wouldn't there have to be enough gas pressure to push the carrier back far enough for the bho to operate? This shouldn't be possible with the gas regulator fully opened, should it? I'm so confused!
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Old November 02, 2017, 06:19   #9
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7 on a type A is not "wide open". 7 on a type B/C is. I have found no standard for max pressure.
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Old November 02, 2017, 08:40   #10
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7 on a type A is not "wide open". 7 on a type B/C is. I have found no standard for max pressure.
What GP says. Look at the port that the regulator covers. As you back it out it takes several turns on the Argy A regulator to fully expose the port.

You say since it was new. Is this a factory Argy?

I would check the actual gas port going into the barrel as the diameter should be around 3/32". Some Argy barrels were sold without the gas block attached and possibly someone put on a gas block and drilled the port.
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Old November 02, 2017, 12:35   #11
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Ok, here goes. The upper is an FMAP, imported by SAC. It appears to be factory assembled. The gas port measures approx. 3/32" and has a ramp cut at the rear of the hole making it appear to be oval in shape, even though it really isn't. With no mods, the regulator ring would uncover the entire round hole, but not the ramped portion. I had to remove some of the plastic part of the handguards to allow the regulator to unscrew far enough to uncover the entire oval. Also, I had to bend the small metal piece that is riveted inside the left handguard so that the small tab on the rear of the regulator wouldn't stop the regulator from turning far enough to clear the entire oval.

I won't get to try it again until later today or sometime tomorrow, but I'll keep you informed. Here's a pic of what I have now.

https://imgur.com/a/G0JfC
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Old November 02, 2017, 15:54   #12
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Originally Posted by M90A1 View Post
Ok, here goes. The upper is an FMAP, imported by SAC. It appears to be factory assembled. The gas port measures approx. 3/32" and has a ramp cut at the rear of the hole making it appear to be oval in shape, even though it really isn't. With no mods, the regulator ring would uncover the entire round hole, but not the ramped portion. I had to remove some of the plastic part of the handguards to allow the regulator to unscrew far enough to uncover the entire oval. Also, I had to bend the small metal piece that is riveted inside the left handguard so that the small tab on the rear of the regulator wouldn't stop the regulator from turning far enough to clear the entire oval.

I won't get to try it again until later today or sometime tomorrow, but I'll keep you informed. Here's a pic of what I have now.

https://imgur.com/a/G0JfC
Nice.
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Old November 02, 2017, 17:29   #13
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Also, I had to bend the small metal piece that is riveted inside the left handguard so that the small tab on the rear of the regulator wouldn't stop the regulator from turning far enough to clear the entire oval.[/url]
That is more than one turn out and it is a type C regulator (tabbed). And your photo shows it is a "standard" (short) FAL gas block, so forget about type A anything. The riveted flange on the HG is to prevent over-rotation on a type B, the tab on a type C. So screw it back in and bend the flange back to perpendicular.

Again, if the bolt is going back far enough for the BHO to catch, it has enough gas. Too much gas does not have any affect on BHO operation. So this is a side issue, but I am convinced it is not related to your BHO engaging after each round.

https://www.arizonaresponsesystems.c...sregulator.jpg
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Old November 02, 2017, 18:19   #14
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I just returned from my shooting spot. With the port fully opened, as shown in the pic above, one round loaded in the magazine, the bolt locks back upon firing. Load another round, remove the magazine and fire, the bolt does not lock back. To my way of thinking, that should eliminate any problem with the bho. How the heck could the rifle be getting that much gas shooting g.i. ball ammo?

To gunplumber: The bolt does not lock back after each round in the magazine, only when single loading rounds.
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Old November 02, 2017, 18:45   #15
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I would check the actual gas port going into the barrel as the diameter should be around 3/32". Some Argy barrels were sold without the gas block attached and possibly someone put on a gas block and drilled the port.
Did you mean the port in the barrel itself, or the port in the gas block?
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Old November 03, 2017, 09:50   #16
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I just returned from my shooting spot. With the port fully opened, as shown in the pic above, one round loaded in the magazine, the bolt locks back upon firing.
As it should

Quote:
Load another round, remove the magazine and fire, the bolt does not lock back.
And it should not.

Your earlier description was that, with a loaded magazine, it locks back after every round. Which is a BHO issue, not a gas issue.

Quote:
To my way of thinking, that should eliminate any problem with the bho.
correct

Quote:
How the heck could the rifle be getting that much gas shooting g.i. ball ammo?
it is possible your gas port is oversized, but it is not a defect according to any of the documentation I have collected, for it to lock back wide open.


Quote:
To gunplumber: The bolt does not lock back after each round in the magazine, only when single loading rounds.
I get that now, but you started with "the bolt locks back after every single loaded shot."

I read that as "every single round in the mag" not "each single-loaded round".

You can measure the gas port by removing the front sight and using a drill bit in the hole behind the front sight. The hole under the regulator is not the one to measure. Standard for a 21" barrel is .098 / 2.5mm .

If that's the size, you just have a very tight gas system.
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Old November 03, 2017, 18:20   #17
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it is possible your gas port is oversized, but it is not a defect according to any of the documentation I have collected, for it to lock back wide open.
If locking back with the port fully opened is correct, what's the sense in having a gas regulator. It would have no purpose.

What I've done so far, with a modicum of success, is to cut a small piece of an old AR gas tube and turn it down so that it's a very tight fit in the gas plug, thus reducing the size of the gas hole in the plug. With the exhaust port on the gas block fully opened, the bolt carrier will not lock back with a single round loaded in the mag. However, it only takes two clicks closed on the regulator to get the bolt carrier to lock back. Next, I'm going to start increasing the size of the exhaust port in the gas block until I have to close the regulator closer to the middle of its adjustment. If I go too far on the exhaust port, I can always drill the bushing in the gas plug a mite larger. Right or wrong, it's working. This rifle is severely over-gassed, somehow, or as gp states, I have a very tight gas system.

Last edited by M90A1; November 03, 2017 at 18:57.
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Old November 03, 2017, 18:40   #18
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If locking back with the port fully opened is correct, what's the sense in having a gas regulator. It would have no purpose.

What I've done so far, with a modicum of success, is to cut a small piece of an old AR gas tube and turn it down so that it's very tight fit in the gas plug, thus reducing the size of the gas hole in the plug. With the exhaust port on the gas block fully opened, the bolt carrier will not lock back with a single round loaded in the mag. However, it only takes two clicks closed on the regulator to get the bolt carrier to lock back. Next, I'm going to start increasing the size of the exhaust port in the gas block until I have to close the regulator closer to the middle of its adjustment. If I go too far on the exhaust port, I can always drill the bushing in the gas plug a mite larger. Right or wrong, it's working. This rifle is severely over-gassed, somehow, or as gp states, I have a very tight gas system.

What you describe will work. I'd leave the barrel port alone. Unless you really feeling it hammer your shoulder or the brass is in the next county, I'd just be done with this tempest in a teapot. I have a para that runs wide open. You screwing around with a factory Argy is absurd. Already grinding shit on the HGs and such. FWIW. My factory Argy has the sight not as centered as I like my builds and have only shot 40 rounds through it, but I'm not going to start screwing with the barrel timing

W
Keep WECSOGing on it and reduce the value $700

But you are the owner.
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Old November 03, 2017, 18:56   #19
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What you describe will work. I'd leave the barrel port alone. Unless you really feeling it hammer your shoulder or the brass is in the next county, I'd just be done with this tempest in a teapot. I have a para that runs wide open. You screwing around with a factory Argy is absurd. Already grinding shit on the HGs and such. FWIW

W
Keep WECSOGing on it and reduce the value $700
Absurd or not, I'm going to make it work the way it's supposed to, and I don't care how much it's worth when I'm done. It'll just end up with one of the grandsons when I'm gone anyway, and at least he'll end up with a fully functioning rifle. And, I'm not touching the barrel port, 'cause there's no need to mess with it to get where I want to be. The gas plug and the gas block will accomplish what I'm looking for.

Thanks for the thoughts. They make me think. Besides, handguards are cheap and I don't think they are correct for this rifle, anyway.
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Old November 03, 2017, 18:59   #20
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Absurd or not, I'm going to make it work the way it's supposed to.
That's just thing, it already does. I have thousands of pages of documentation on the gun from many countries, and while there are minimum settings (3.5 FAL, 4 L1A1, 5 C1) I have yet to find any documentation stating that functioning on 7 (L1A1=11), is a defect.

I had a SAR 48 Para NIB that functioned with gas on 7. When I measured the gas port it was .098". It is not supposed to work on a 17.2" barrel, but it did. So I left it alone.
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Old November 03, 2017, 19:19   #21
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That's just thing, it already does. I have thousands of pages of documentation on the gun from many countries, and while there are minimum settings (3.5 FAL, 4 L1A1, 5 C1) I have yet to find any documentation stating that functioning on 7 (L1A1=11), is a defect.

I had a SAR 48 Para NIB that functioned with gas on 7. When I measured the gas port it was .098". It is not supposed to work on a 17.2" barrel, but it did. So I left it alone.
Bingo...I've learned a lot here from you and this board. Reliability comes from not panzy assing the gas system to save brass like some of us tend to do. It's a non-issue. Spend your money on ammo to wear the gas system. Shoot a half case and come back
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Old November 03, 2017, 19:22   #22
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That's just thing, it already does. I have thousands of pages of documentation on the gun from many countries, and while there are minimum settings (3.5 FAL, 4 L1A1, 5 C1) I have yet to find any documentation stating that functioning on 7 (L1A1=11), is a defect.

I had a SAR 48 Para NIB that functioned with gas on 7. When I measured the gas port it was .098". It is not supposed to work on a 17.2" barrel, but it did. So I left it alone.
In the end, I'm having fun making this thing adjustable in both directions. It just dawned on me that the real purpose of the gas regulator is probably to allow the shooter to introduce more gas into the system of a very dirty rifle, but since my rifle will never get that dirty, I'd like the regulator to function as a tuning device for different loads. Heck, I like playing and I'm not hurting anyone or the rifle.

I do see your point, Mark. I'm just doing it anyway.
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Old November 06, 2017, 22:07   #23
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Ok, got it where I want it. Opened the exhaust port slightly and now the bolt locks back with the regulator six clicks in from fully open. That leaves me five more until it's fully closed. The brass is ejected 4-6ft. away at 2 o'clock when firing LC ball and slightly less when shooting Fed. GMM. This is exactly what I was after.

I also installed a JARD 4lb. trigger assembly while I was at it, and that is the best mod I've made to the rifle. Pricey, but what a difference in the trigger pull. Most of you would be horrified at what I had to do to make the installation work, but I got it done. Really, all that was necessary was to remove the hammer-travel limiting cross-pin from the lower, and then the rest was a piece of cake. I can't figure out what the Argentinians were thinking with that pin. None of the other metric FALs use it. An FSE hammer won't work with that cross-pin in place either. Tried that, too.
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Old November 07, 2017, 08:48   #24
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Ok, got it where I want it. Opened the exhaust port slightly and now the bolt locks back with the regulator six clicks in from fully open. That leaves me five more until it's fully closed. The brass is ejected 4-6ft. away at 2 o'clock when firing LC ball and slightly less when shooting Fed. GMM. This is exactly what I was after.

I also installed a JARD 4lb. trigger assembly while I was at it, and that is the best mod I've made to the rifle. Pricey, but what a difference in the trigger pull. Most of you would be horrified at what I had to do to make the installation work, but I got it done. Really, all that was necessary was to remove the hammer-travel limiting cross-pin from the lower, and then the rest was a piece of cake. I can't figure out what the Argentinians were thinking with that pin. None of the other metric FALs use it. An FSE hammer won't work with that cross-pin in place either. Tried that, too.
It is a block to prevent installing a FA hammer. I cut it, solder the ends, and then machine smooth. Found that fills the holes better than welding the casting.

I hope you like the Jard - every one I've installed for customers they have eventually removed, as it is unreliable.
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Old November 07, 2017, 09:27   #25
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I hope you like the Jard - every one I've installed for customers they have eventually removed, as it is unreliable.
I'll report on the JARD if mine becomes hinky. Is the unreliability related to wear? It seems to be a pretty straight-forward design, much like the trigger in an AR. I can always install the FSE if it does, now that that damned cross-pin is gone.
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Old November 07, 2017, 10:24   #26
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I'll report on the JARD if mine becomes hinky. Is the unreliability related to wear? It seems to be a pretty straight-forward design, much like the trigger in an AR. I can always install the FSE if it does, now that that damned cross-pin is gone.
Erratic performance - it's been several years, but I think inconsistent reset was the main issue. Nice idea. Sound principle. Did something similar with Harold @ FSE, but during testing, I was able to adjust it (outside parameters) to get controlled full-auto. So the project died. Like the early Timney 10/22 trigger I tested and got hammer follow on earlier (1970s) trigger housings, but not on later ones (1990s). I think that there is enough subtle variance that the only sure way is to make the complete trigger box as a drop in unit, rather than having individual components adjustable. Which is what Timney ended up doing.
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Old November 07, 2017, 11:21   #27
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Erratic performance - it's been several years, but I think inconsistent reset was the main issue. Nice idea. Sound principle. Did something similar with Harold @ FSE, but during testing, I was able to adjust it (outside parameters) to get controlled full-auto. So the project died. Like the early Timney 10/22 trigger I tested and got hammer follow on earlier (1970s) trigger housings, but not on later ones (1990s). I think that there is enough subtle variance that the only sure way is to make the complete trigger box as a drop in unit, rather than having individual components adjustable. Which is what Timney ended up doing.
After working with the adjustments on the JARD, I can see where inconsistent reset could be caused by wear between the disconnector and its adjustment screw. I'll keep a close eye on that area.
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