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Orion the Hunter
December 12, 2017, 21:58
Put together I Imbel and went to try in out today to set the Gas Regulator. Started with it opened a little and worked it down...shell by shell...until it was fully closed...Still doesn't cycle. Double checked gas plug to make sure it was the right way...swapped out with another gas plug. No change. Removed Dust Cover to see if the carrier moved at all...very hard to tell, but it looked like it short stroked.

Changed out Gas Tube, Regulator, Piston and Spring...No Change.

Piston goes all the way through gas tube, no hang ups.

Here is some things I am going to try, any thoughts?

I checked out the action and it seems that there may be a slight heavier stock spring than the other. I am going to swap out the lower with one that I know works to eliminate that.

NOTE: During the initial makeup of the rifle, there was a burr, or carbon or something in in the way of the piston stroking through. I used a round file to remove it. My next guess is that, maybe that carbon build up is in the Gas Hole as well? I don't have a #40 or #41 drill bit handy (but might run to town tonight for one). I guess simply (and carefully) drill straight down through right? I read where it is wise to put a 1/4 dowel in the barrel to avoid punching to far through?

What size should I use? #40 or #41 or ??? Maybe open it up even more?

Any thoughts or tips here?

The only final thing I can think of is that there is something bazaar with the Gas Block? How much of a PIA is that to swap out the block? In GP book, it looks like he uses a chunk of angle iron to move it. How does one make sure the replacement Gas Block is back in the right place? Should a novice even attempt this or just bite the bullet and buy another Barrel or send it in?

Anybody have any other ideas I can try out?

Grrrrrr....

Invictus77
December 12, 2017, 22:07
any thoughts?

I checked out the action and it seems that there may be a slight heavier stock spring than the other. I am going to swap out the lower with one that I know works to eliminate that.

Trying a known lower would prove this out, but I would recommend you pull the recoil spring, clean the tube & spring, and lightly lube as a next step.

Orion the Hunter
December 12, 2017, 23:17
At my wits end...

Changed out lowers with a lower that is confirmed to work. Some problem, damn thing does not cycle.

Seems like the only options left is to try either drilling out the Gas Port, Replace the Gas Block or probably just as cheap to replace the whole damn upper.

It is an IMBEL Receiver, it seems to cycle without any difficulties...Has anyone ran into something odd? I was thinking maybe it was hanging up when retracting..nothing out of the ordinary from the last builds though...

Stupid question: What use is the pin for that is set into the Gas Block? I was thinking that it is to secure the Gas Tube so it doesn't rotate but that doesn't seem to be the case...WTF?

Anyway, back to the nightmare.

Ghost
December 12, 2017, 23:40
This may well be your issue. The small pin is indeed to keep the tube from rotating. The tube will have 2 "U" shaped notches. One is posisiond at the top and the other at the bottom the bottom one will have a flat that the pin interacts with keeping it from rotating, I've seen tubes with the f!at on top and bottom. If the tube can rotate it sounds likely it isnt screwed in all the way. Also the orentation may be incorrect and the holes arent loned up.

At my wits end...

Changed out lowers with a lower that is confirmed to work. Some problem, damn thing does not cycle.

Seems like the only options left is to try either drilling out the Gas Port, Replace the Gas Block or probably just as cheap to replace the whole damn upper.

It is an IMBEL Receiver, it seems to cycle without any difficulties...Has anyone ran into something odd? I was thinking maybe it was hanging up when retracting..nothing out of the ordinary from the last builds though...

Stupid question: What use is the pin for that is set into the Gas Block? I was thinking that it is to secure the Gas Tube so it doesn't rotate but that doesn't seem to be the case...WTF?

Anyway, back to the nightmare.

Orion the Hunter
December 13, 2017, 02:10
The pin-hole on my Gas Block appears to be slightly wallowed out to the point where the pin slips right through. I discovered that the pins for the charging handles seem to be the exact same size as the Gas Tube Pin (correct me if I am wrong). In fact I tried a pin from another barrel and it too slid right through as well, so I had to tap it with a hammer to distort the pin a tad, and it was able to hold in place with a pin punch.

After trying (2) Gas Tubes (I tried another one to make sure there wasn't a hairline crack or something) and tightened them up positive then backed them off so the holes are at the "8 & 4 o'Clock Position).

Still No Cycle.

When I removed the handguards to see if the tube had somehow rotated...they hadn't...and were still at the "8 & 4" position.

Strangely on the other builds of mine (6 so far), the Gas Tubes have been pinned loosely in place and they have shot just fine. In fact, I was wondering that maybe to was made up too tight? I still can turn the tube by hand (using a little grip muscle)...that is why I am thinking maybe there is something a-fowl with the Gas Block? I did some reading and it doesn't look too difficult to change them out..maybe just some headaches trying to get them to align.

Other than that, what else could it be? It looks so simple, there is only a handful of parts that are not very sophisticated...I guess I could punch out the Gas Block Pin and see if the Gas Block moves freely or something wierd? Maybe the Gas Block was put on incorrectly by someone else (after all it was a ebay purchase about 4 years ago).

I guess here is a good question to ask: What are the some of the reasons people have had to change out Gas Blocks (other than the obvious...Like "it was Cracked or Broke"). Once I get it removed, what should I check for? (hole size is suppose to be Drill bit size #40 or #41 right?) I guess I could Mike it to compare with other FAL barrels I have? Any other pointers? Hints? Lessons Learned? etc?

OLDMANPBK
December 13, 2017, 02:38
Good stuff here if you haven't seen it yet.
http://www.falfiles.com/forums/showthread.php?t=108077

Orion the Hunter
December 13, 2017, 02:44
I am almost heading in the direction of trying to drill out the Gas Port Hole a bit.

Question: Anyone try drilling out the Gasport with Gas block still attached or should I remove it first.

Thanks

OLDMANPBK
December 13, 2017, 03:34
Leave the gas block on. You may have to open up the port but rule out everything else before drilling.

Golf3Alpha
December 13, 2017, 06:34
What manufacture barrel is it? I recently installed a DSA 18" barrel that had no gas port hole at all. Does the piston show any carbon buildup? If not, you ain't gettin' any gas.

MAINER
December 13, 2017, 10:38
For reference;
Number drill sizes,
#42 = .0935"
#41 = .0960"
#40 = .0980"
#39 = .0995"
#38 = .1015"

I would try these bits as a gauge using the shank end to determine Port size or possibility of a blockage.

I know your problem is frustrating, but as mentioned above, drilling the Port should not be necessary if you can get a #40 or #41 Drill shank to enter the bore.

The Gas Tube should have a smooth flat end toward the Gas Block, erosion produces a thin ragged edge in time. The Gas Tube is screwed in until tight, then backed off only enough to line up the flat to drive the retaining pin in place. Ten degrees or so of wobble is normal.

Good luck with your rifle.

gunplumber
December 13, 2017, 10:57
21" barrel?

Gas regulator flush to gas block and not 360 degrees out and back to 1?

piston .430-.001?

outer return spring min 19", 20" better

hammer not dragging on receiver cutout?

cocking handle pin is shorter than gas tube pin, but usually works.

gas port (21") @ .098-.100?
.116 (18"), .118/3mm (16"),
Yes, you can enlarge to .106" then to .110"
but rule out everything else first.

No reason to remove block. To verify alignment on reinstall, I use a .010" allen wrench and feel through the gas block, to see if the barrel gas port is centered. If reinstalling same block, can also just look at hole for retaining pin, but it's not as precise.

Orion the Hunter
December 14, 2017, 03:40
Thank you everyone for your suggestions and observations.

Here is what I "Think" the issue is:

Ok, after swapping out every spare part that I had in the Gas System and then some, as mentioned in the suggestions, I tried sticking a #38 down the Gas Port..No Go!

So, I went ahead and used the 1/4" dowel maneuver and drilled up from a #38 to a #40 and decided to stop there. Tried it out...No Go!

I located a Third Gas Tube and Tried that. Now, as I mentioned up front, the Gas Tube that came with the kit was "aggressively hand tight to make up". I replaced it with a Third Gas Tube annnnnd...Go! ( I actually tried another one I had and it didn't work either).

Next, I decided to test the First Gas Tube that came with the kit by threading it all the way in first, then backed it off to "*8 & 4"...No Go. Then I backed it off another 360-rotation back to to "8 & 4" and so tried it one more time still looser yet. No Go! No Luck! (I was thinking maybe the 2-slots in the Gas Tube were not positioned correctly based on the threads?)

So I put the Third Gas Tube back in , and tightened it fully, then backed off to "8 & 4"...Go! As noted on the other Imbels I built, the tube was pinned in place yet was "'sloppy"...just like this third tube was.

What was the problem? I freaking have no idea! Both tubes look good ( the only difference that I can see is that one threads in a little tighter than the other one does).

Unfortunately, The Third Gas Tube (final replacement) requires the regulator to be almost 100% closed.

Is that a Bad Thing? (certainly not a good thing?)

If I was going to give my best educated guess: "Something haywire with the Gas Block..."

Anyone have Thoughts or Ideas?

Capt D
December 14, 2017, 07:17
Alrighty...I've read through this entire thread and, prior to drilling your gas port, or even messing with the gas block at all (I'm hoping it hasn't been altered yet?) here is the recommendation I would offer...

You've mentioned '8 & 4' a few times. I presume you refer to the orientation of the small vent holes located about 1/4 of the way back from the threaded end of the gas tube, correct? If those holes are facing 'down' at the '8 & 4' positions when installed, that may very well be your problem. Please see the photos of my own NOS gas tube as a reference: https://photos.app.goo.gl/Ry7J4eNGxAiBjX3Y2

(CAVEAT: If your gas tube has gas relief holes at both 6:00 AND 12:00 positions on the threaded end, the following suggestion is nullified and more in-depth problem-rooting is needed)

Seen in the first photo, with the orange circled areas, you'll notice the lateral vent holes are facing upward @ 10 & 2, and a flattened portion is seen on the threaded area at 12 o'clock. You want that flattened area (without relief hole) facing UP, which would place the lateral vent holes oriented at '10 & 2' NOT '8 & 4' as previously mentioned. In the second photo in my link, you'll see the holes are not visible (i.e., facing downward at 8 & 4) and there is a gas relief hole visible on the threaded portion -- you will want THIS hole facing DOWN at 6 o'clock, towards the gas port.

Again, provided that your gas tube's threaded portion is identical to the one in my photos (i.e., only ONE hole in the threads), you will want to do the following: Thread the tube into the gas block until it bottoms out, then back it out just slightly (should not even be half a turn) until those lateral vent holes are at 10 & 2, and you can see through the pin hole (use a light if necessary). Install the gas tube retaining pin. It is okay if it doesn't fit tightly, as the gas regulator keeps it in place. If it is tight, be very careful not to bugger up your gas regulator threads tapping the pin in. Just make sure it is inserted fully, that the gas tube is not allowed to freely turn, and you can feel 'detent stops' against the retaining pin when gently attempting to rotate the tube. As stated before, a little play is okay, as this is designed to prevent binding...just ensure the tube will not rotate freely with the retaining pin installed.

One thing I do with my gas tubes is, after carefully degreasing the threads, I mask off the area just behind thee threads (as well as masking the inside of the tube) and I use an epoxy-based high temp rattle-can paint to lightly coat the threads. Just be sure it doesn't get inside the tube, because it will atomize during firing and gum up the inside of the tube...it's a bitch to remove; ask me how I know! The paint will 'seal' the threads somewhat, yet will allow the small amount of play you want in the gas tube fit. I've used this on a number of gas tubes and have never had it cause issues, works like a charm.

Once all of that is done, and assuming it goes 'according to plan', do the free-movement check on the gas piston, to ensure it moves resistance-free through the gas tube assembly. Any burrs or hang-ups can cause short-stroking of the piston. Once that is done, I suggest you take a bore brush (I use a .45 cal brush) and a section of cleaning rod, chuck it up in a drill, and gently scrub the inside of the gas tube and gas block, from back to front. This will ensure any potential crud is removed that could bind up the piston, as well as as give a tactile feel of how smooth the inside of the assembly is. Once all that is finished, assemble as usual, and head to the range!

I apologize for the wordiness of my reply, but I know how frustrating issues like this can be, and I wanted to be as thorough and concise as I possibly could. If you have any questions or concerns, please feel free to PM me your phone # and I'll happily talk through things with you over the phone. Best of luck, do keep us apprised of your progress... -Art

AFeod
December 16, 2017, 01:42
Art... you da man
:bow:

Orion the Hunter
December 20, 2017, 15:02
Thanks for the explanation! I was scratching my head for awhile...and then the light finally clicked on....in that the Gas Tube Example that you show in your picture have only has (1) Slot Cut in it. (I didnít know they made them 1-slotted...I thought they were all 2 slotted???). Anyway, yes, all of the Gas Tubes I tried were 2-Slotted. As mentioned, for some reason the only Gas Tube that worked was the one that was threaded up loose & sloppy. Then the regulator had to be threaded almost all the way to close off the Gas port hole, so the Bolt/carries would cycle.

The other FALS I built, did not require for the regulator to be threaded to close off the Gas Port Hole....only part way.

I think what I am going to do is purchase a newer Gas Tube and try that first. If that doesnít work...the only thing left is the Gas Block...and my gut is telling me somehow....that is where the problem is...?

hkshooter
December 20, 2017, 15:51
Look at the journal where the gas block and barrel meet. If there is a substantial amount of powder staining and carbon build up outside of the journal then it may be leaking excessively and bleeding off much needed pressure.
How much wiggle is there in the gas tube when screwed in and pinned? This is subjective, really, but if there is excessive wobble then the tube is too loose in the threads, allowing gas to leak around the tube instead of going through it. I like my tubes to be nearly, but not quite, wiggle free. Where the two slots are in the front of the tube, there is obviously material missing and years of abuse, removal and reinstallation, and plain hand fisttedness can bend the two ears in, causing a very loose in the block tube fit.
Finally, the threads in the GB can be eroded away, causing looseness and leakage. Most of the time when I've seen this a new tube won't fix it and the problems is the tube keeps getting blown out of the GB. Time for a new GB or to solder in a short tube, ala StG58.