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Old July 09, 2007, 19:57   #1
Scott V2
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How does a gas block get worn out?

I am fiddling with my first build. I think the gas block is letting too much gas through past the plug. My plugs all measure .451 diameter. My gas block allows the plugs to wiggle quite a bit compared to another stg gas block build which runs great. Is it gases that could erode a block?
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Old July 10, 2007, 05:04   #2
NoNotAgain
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Yes it is.

Not as bad as a 220 Swift but long term just the same.
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Old July 10, 2007, 07:46   #3
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There are armorer's tools for checking gas blocks to determine wear.
But, I don't think they wore out that often or at least more often than the barrel in regular service use.

If it is on a decent barrel, it is probably ok. I have an L1A1 Aussie barrel that seems to do a better job of covering the forward end of a gas plug with carbon than any of the others of mine. It functions 100% on a reasonable gas setting.

The key to reliable functioning is to have enough gas driving the piston to cycle the weapon. FALs tend to leak gas all over the place. Coming forward around the gas plug, past the gas tube threads and past the piston as well as what is allowed to divert through the exit hole at the top pf the tube. If it doesn't cycle, you can try different gas pistons and springs or even open up the port in the barrel a bit to tune it in. Takes some fiddling sometimes.
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Old July 10, 2007, 09:21   #4
Scott V2
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Quote:
Originally posted by bykerhd
There are armorer's tools for checking gas blocks to determine wear.
But, I don't think they wore out that often or at least more often than the barrel in regular service use.

If it is on a decent barrel, it is probably ok. I have an L1A1 Aussie barrel that seems to do a better job of covering the forward end of a gas plug with carbon than any of the others of mine. It functions 100% on a reasonable gas setting.

The key to reliable functioning is to have enough gas driving the piston to cycle the weapon. FALs tend to leak gas all over the place. Coming forward around the gas plug, past the gas tube threads and past the piston as well as what is allowed to divert through the exit hole at the top pf the tube. If it doesn't cycle, you can try different gas pistons and springs or even open up the port in the barrel a bit to tune it in. Takes some fiddling sometimes.
It is a new GPG barrel that I traded another member for. I have not exhausted all of the "tests" for leakage yet, but it is obvious that the plug fits noticeably looser in the gas block compared to other barrels that I have. The rifle would not cycle with the gas hole completely covered, and yes it was not set on "G". The gas hole is also not obstructed by the gas tube.
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Old July 10, 2007, 10:27   #5
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I had a gas block that was so wore out that the plug wouldnt stay in place. You could insert it and turn it without depressing the pin all the way around to G. The fix....bought a new gas block.
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Old July 10, 2007, 10:49   #6
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Gas might erode a gas block.

Rust might erode a gas block.

But my guess is that Snuffy scraped the bejeezus out of it to get it cleaner than it needed to be.
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Old July 10, 2007, 10:49   #7
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There are probably still some brand new Metric FAL gas blocks floating around. They are NOT drilled for the cross pin. Lots of work to fit one I would think. The better bet might be a used one off a low mileage Imbel barrel that ended up in someones junk parts pile due to a pitted bore or something.
That is, if your gas block really IS worn out.
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Old July 10, 2007, 11:30   #8
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If I had to pick a number, I'd say 50% of all the G1 gasblocks are worn to unserviceable.

probably a combination of corrosive primers, condensation and 30 years of Turkish weapon maintenance.

I can['t recall more than a handful of non G1 gasblocks that were worn oversize without obvious visible corrosion (like the Aussie blocks)
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Old July 10, 2007, 12:24   #9
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I agree with GP on the worn G1 blocks. Virtually, all of them need gas port enlargement to compensate for gas flow.

I speculate, If those G1 bbl's ever returned to FN, There would probably be a 90% Unserviceable rate.

In some cases, A new DSA Gas plug($35) and new Gas tube($30), can be enough to compansate for the loose tolerances of the worn G1 block. At least enough to get a generous service life/extension.

Best option:
New gas block - $40
Install - $40
VG or new Gas Tube - $30
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Old July 11, 2007, 02:06   #10
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gas block

I have the gas block no-go tool. You may borrow it if you like.

If that barrel was purchased from GPG with a gas block on it, then I was the one who put it there. That is why I have the no go tool; I used it when selecting gas blocks for those barrels. That's not to say that it isn't possible it's bad, just that I did look them over pretty good before installing them.

Shoot me your address and I'll send you the tool.
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Old July 11, 2007, 05:03   #11
Scott V2
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Re: gas block

Quote:
Originally posted by adam762
I have the gas block no-go tool. You may borrow it if you like.

If that barrel was purchased from GPG with a gas block on it, then I was the one who put it there. That is why I have the no go tool; I used it when selecting gas blocks for those barrels. That's not to say that it isn't possible it's bad, just that I did look them over pretty good before installing them.

Shoot me your address and I'll send you the tool.
Address incoming.

Adam,

I really appreciate the offer. I am not 100% that it is the gas block at this point. This is my first real time tinkering and the opportunity for operator error/learning is high

-Scott
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Old July 11, 2007, 18:43   #12
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Hello Adam,
Sir, all I can say is that if you did the work on that barrel and you are willing to send a no-go tool to a stranger to help him with it, you are a class act! I really do like being a part of this community.
Take care,
Rabbit
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Old July 11, 2007, 19:19   #13
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Quote:
Originally posted by K.R. Rabbit
Hello Adam,
Sir, all I can say is that if you did the work on that barrel and you are willing to send a no-go tool to a stranger to help him with it, you are a class act! I really do like being a part of this community.
Take care,
Rabbit
Nah, I'm a bum, just ask anybody.

A very behind schedule bum at the moment. Always happy to help, though, especially if I mighta overlooked something in the first place. If Scott has a overly worn gas block, I'll likely be replacing it. Those barrels went for good money, and worn out gas blocks were NOT acceptable for service.
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Old July 19, 2007, 06:39   #14
Scott V2
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with Adam's tool, I think it is the gas-block itself. the tool slides in pretty easy and leaves only about 3/8 of the flat spot showing
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Old July 19, 2007, 10:14   #15
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Quote:
Originally posted by Scott V2
with Adam's tool, I think it is the gas-block itself. the tool slides in pretty easy and leaves only about 3/8 of the flat spot showing
I'd say the gas block is toast. The tool should just barely insert into the block and almost get stuck in doing so.
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