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Old August 25, 2005, 19:29   #1
Beagle
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Question Gas Block Removal

I am building a STG 58, I have had this kit for a while, I am in the process of timing the barrel before final tightening. The gas block has the short piston tube brazed in. I have a long tube that I want to use. Is there any no-no's that I should know before I remove the pin and gas block to replace with another gas block? This is my first gun build. Any advice would be extremly appreciated, as I do not want to screw up this build. I have bought the tools to do this project, I am a machinist by trade, but I have never tried to build a gun before.
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Old August 25, 2005, 20:36   #2
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I should think it wou;d be a lot easier to unsolder the short tube and replace with the one you wabt to use---Mapp gas torch from Sears will work.
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Old August 25, 2005, 20:45   #3
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The problem with a FAL or any other assembly is the learning curve.

You need to put one together as simply as possible before moving up to more complex things. Put the long tube on the gas block and get it firing before you experiment further.

After a bit, the process is simple.
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Old August 25, 2005, 21:08   #4
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Why remove the short tube ?
The short tube was the armory "fix", as I understand it, for worn gas blocks and/or loose gas tubes when the guns were overhauled. DSA has been offering barrels with short tubes for a long time. The only issue with them is lining up the gas tube properly so the piston cycles as it should. That is not that difficult. The short tubes are usually trouble free after they are lined up, seal better than the long gas tubes and are "correct" for the STG.
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Old August 27, 2005, 21:12   #5
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My kit, as I understand it, is supposed to be one that never saw field usage.
Everything appears to be brand new, all matching, no wear on anything.
So what is this Armory Fix? Do I have a bad gas block? If so How do I check the block to see if it is in spec? The only thing that appears to have any form of usage is the piston head, a few pits and the edges are rounded, not sharp. I don't know if this normal for the edges, when I say rounded, I mean barely. The pits look like someone forgot to clean the piston tip. The rest of the piston looks like new. The entire kit appears factory new.
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Old August 27, 2005, 21:28   #6
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Beagle, what they are saying is to stay with the short brazed on gas tube that came wtih your barrel.

The short tube is the "armory fix". The long tube was prone to more problems.

Your gas block will be fine, if this kit is as what you have described.

On your first build, take it slow and keep any modifications to a minimum.

You will probably enjoy a fine shooter that way!

Use the gas piston that came with the kit, then if you have any problems with the gas piston, you can change it out. The end that faces forward is where the gas bleedoff hits the piston....there will be more wear there then anywhere else. But what seals the piston is the lobes on it, if they look good (should measure .429 to .430) you are good there as well.
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Old August 27, 2005, 21:31   #7
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As far as I know, NOBODY has ever found a verified reference to establish the reason for the "short" gas tube system. There are several plausible theories. None of them documented.

The STG is "correct" with the short gas tube OR the long gas tube.

I would not remove the soldered tube. Even if the gas block is otherwise pristine, it will be difficult to remove all the solder residue from the inside of the gas block. So, when you try to screw-in the replacement tube, the solder residue might work like a swage, and smoosh-down the forward end of the replacement tube, reducing the inside diameter of the most important area of the tube.

The gas tube aint broke. Don't fix it.
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Old August 27, 2005, 21:44   #8
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yep, If It ain't broke...

I have two matching no's STG's, one has the short tube, the other has the full length. It makes no difference.
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Old August 28, 2005, 22:00   #9
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Gentlemen, you have been very, ...no extremly helpful. I sanded my sholder down to get the proper hand timing, only needed a couple of thou. to be removed to get it in time. Now have the barrel in the vice, (barrel vice tool), and the reciever wrench installed, (with tape on the reciever of course). Installed the timing rods and am ready to tourque and time the barrel. Do any of you know who might do green parkerizing? My rifle and reciever match, but I have a couple of small items that are black and I would like them to match the rest of the rifle. Again Thank You!!!

P.S. I will let you know how the torquing goes.
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Old August 29, 2005, 07:10   #10
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I'm not a fan of the two rod method. If the sight ears appear to be in good shape on the gas block, you can use a magnetic level across them and set the barrel level in the vise. Torque up the receiver and finish with the level across the rails of the rear part of the receiver. When barrel and receiver match up as both level, check back and forth a couple tiomes to be sure, you should be set. Check it with the two rods if you like. My fancy level is a Craftsman I bought on sale for $ 5.
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Old August 29, 2005, 07:39   #11
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Quote:
Originally posted by bykerhd
I'm not a fan of the two rod method. If the sight ears appear to be in good shape on the gas block, you can use a magnetic level across them and set the barrel level in the vise. Torque up the receiver and finish with the level across the rails of the rear part of the receiver. When barrel and receiver match up as both level, check back and forth a couple tiomes to be sure, you should be set. Check it with the two rods if you like. My fancy level is a Craftsman I bought on sale for $ 5.
Wastrel! Go to the Ace Hardware and look in the close out bins for the $2 levels. Works just as well as the high priced stuff.
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Old August 29, 2005, 08:24   #12
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If you have a FAL barrel with a worn out gas block, how does cutting down the piston tube improve the situation?
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Old August 29, 2005, 10:48   #13
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Eclipse,
He never said he had a worn out gas block. He said he had a soldered on short gas tube and was thinking about changing it.......that is where the gas block came in.

My opinion was, if its not broke don't fix it!! Use the short tube till its prooven it has problems, then worry about changing it.
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Old August 29, 2005, 20:29   #14
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The short gas tube brazed on is a product improvement that was standardized on all new production Stg -58s after about sn 100,000.


It was also retrofitted to earlier production Stg barrels as necessary at overhaul or maintainance.

It would be a big mistake to replace the short gas tube with a long gas tube. On later production barrels the hole for the retaining pin for the gas tube was omitted so the only method of attachment was brazing.

Keep the barrel as it is and use it with the short system.

By the way, all new production DSA barrels use the brazed on short gas tube system. Argentine barrels also used the brazed short gas tube at some point.

Last edited by chrsdwns; August 29, 2005 at 20:34.
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Old August 31, 2005, 05:30   #15
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I have decided to leave the short gas tube on this rifle. I have torqued the recuever down, everything went together very easily. I'm ready to headspace now, don't expect any difficulties there, I have a match set of guages to do the job. Should be running in a couple of days, I will let you guys know how it runs. I need to know who does green parkerizing, kit and reciever came through green, want to keep it that way. I have some small parts that are black and want to match them. Again, thanks for all the info.
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Old August 31, 2005, 07:00   #16
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Quote:
Originally posted by Beagle
I have decided to leave the short gas tube on this rifle. I have torqued the recuever down, everything went together very easily. I'm ready to headspace now, don't expect any difficulties there, I have a match set of guages to do the job. Should be running in a couple of days, I will let you guys know how it runs. I need to know who does green parkerizing, kit and reciever came through green, want to keep it that way. I have some small parts that are black and want to match them. Again, thanks for all the info.
Try sledgehammer, a member.
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Old August 31, 2005, 07:19   #17
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park

The greenish tint you are referring to is a product of oils reacting with the phosphate coating. Originaly, years ago, it was all very much a dark charcoal grey. I have parked a good bunch of StG parts, and they all come out remakably dark in just the standard Mang. phosphate. There may be other phosphate solutions out there that offer that kind of color; I don't know. Ask one of the park professionals like Rickets. You are certainly not the only one who'd like to match the aged finish on their kits.
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Old March 11, 2018, 07:50   #18
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Quote:
Originally Posted by DABTL View Post
The problem with a FAL or any other assembly is the learning curve.

You need to put one together as simply as possible before moving up to more complex things. Put the long tube on the gas block and get it firing before you experiment further.

After a bit, the process is simple.
Quote:
Originally Posted by DABTL View Post
Wastrel! Go to the Ace Hardware and look in the close out bins for the $2 levels. Works just as well as the high priced stuff.
Quote:
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Try sledgehammer, a member.
Going through some old posts, as I have one to do, therefore trying to get smart and learning up on gas block removal.....Found some helpful information from a once fellow member.

Good thing he was banned. DABTL DABTL DABTL. Someone might have had their delicate sensibilities violated.
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Old March 11, 2018, 07:55   #19
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I just did one for a customer. The short tube was crimped by someone grabbing it with vise grips or something similar.....

Heat with map gas and unscrew after removing pin. Clean the inside of gas block with wire brush while hot. I bead blasted and re-parkerized barrel assembly and gas block before installing long gas tube.

Hope this helps.
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Old March 11, 2018, 08:34   #20
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Originally Posted by 187 View Post
I just did one for a customer. The short tube was crimped by someone grabbing it with vise grips or something similar.....

Heat with map gas and unscrew after removing pin. Clean the inside of gas block with wire brush while hot. I bead blasted and re-parkerized barrel assembly and gas block before installing long gas tube.

Hope this helps.
Mine is not a STG short vs. long gas block/tube issue. Merely removing the gas block from a NBC Argy barrel....and replacing with an Indian....Going to use (or should I say try) this rather than an Indian sewer pipe for the barrel.

Thanks for the info.
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Old March 11, 2018, 08:37   #21
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Originally Posted by Aeroscout View Post
Mine is not a STG short vs. long gas block/tube issue. Merely removing the gas block from a NBC Argy barrel....and replacing with an Indian....Going to use (or should I say try) this rather than an Indian sewer pipe for the barrel.

Thanks for the info.
One problem though.....the FH is threaded opposite the barrel threads......hopefully the threads can be reversed without having to cut, crown rethread?
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Old March 13, 2018, 08:06   #22
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One problem though.....the FH is threaded opposite the barrel threads......hopefully the threads can be reversed without having to cut, crown rethread?
Sorry, but no.
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Old March 13, 2018, 12:07   #23
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Sorry, but no.
Talked to GP a bit on this also. Seems the gas port on the Indian gas block and Argy barrel are not in proper alignment either. So this idea is out also.

Per Mark's advice I believe my answer is to be found in an Aussie L1A1 barrel. Gas port is properly aligned and barrel is threaded properly for the FH (I am pretty sure of this anyway). Not only that but they are relatively generic as far as stamps and proofs are concerned so it would not be so blatantly obvious that the stamp happy Brit barrel found on my Indian does not belong.
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