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Questions about gas system

This is a discussion on Questions about gas system within the Accuracy forums, part of the M14 M1A Forum category; Curious, What ammo do you shoot and what type of cleaning maintenance do you typically do on the gas cylinder. You leaving any cleaner in ...


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Old March 20th, 2017, 07:55 PM   #16
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Curious,

What ammo do you shoot and what type of cleaning maintenance do you typically do on the gas cylinder.
You leaving any cleaner in there maybe?

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Old March 20th, 2017, 08:17 PM   #17
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Both handloads and Hornady Match, 168 and 155. Handloads 168 gr AMAX 39.5gr IMR 3031.

Don't have the drill bits for piston and Sadlak is out of stock (except I've got the gas plug bit which surprises me how much carbon build-up in it.

I turn off the gas system for barrel maintenance/cleaning.
Gas cylinder itself I don't do much if anything, don't recall seeing any buildup in it...

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Curious,

What ammo do you shoot and what type of cleaning maintenance do you typically do on the gas cylinder.
You leaving any cleaner in there maybe?

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Old March 20th, 2017, 08:19 PM   #18
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Copious amounts of Hornady 168gr BTHP and Hornady 155 OTM, plus my own loads of 165 gr and 168 gr with 39.5gr of IMR 3031. 50/50.

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What ammo are you using?

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Old March 20th, 2017, 08:31 PM   #19
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Looking at the gas cylinder?

What did you do?

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You need too do this, and it will be much cleaner.

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Old March 20th, 2017, 08:43 PM   #20
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I think there is something seriously wrong with the gas cylinder. Either something inside is scraping or it is oversized. Are there any cracks?

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Old March 20th, 2017, 08:53 PM   #21
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Kurt I can't see any cracks, looking into it with a flashlight

How about it passes the tilt test (until it warms up from shooting) then it is real "sticky"
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I think there is something seriously wrong with the gas cylinder. Either something inside is scraping or it is oversized. Are there any cracks?

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Old March 20th, 2017, 09:13 PM   #22
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Kurt I can't see any cracks, looking into it with a flashlight

How about it passes the tilt test (until it warms up from shooting) then it is real "sticky"
I'm not the least bit qualified to speculate, but generally speaking, when things heat up, the stuff gets looser, unless there's actually residue inside the system that's getting tacky when hot.

Do you think maybe the heat, combined with the gas plug torquing the gas cylinder lock due to excessive play might be pulling an edge up and scraping the piston?

Is it all smooth on the inside, visually and to touch?

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Old March 20th, 2017, 09:46 PM   #23
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Interesting, my piston test when actively shooting between shot strings is very sticky and does not slide easily, maybe with shaking the rifle, as opposed to when things are cooled off.

I see no residue or fouling in cylinder, nor any roughness.

What you suggest about gas plug torque possibly causing binding because of gas lock 'play' is intriguing, I know I overtorqued the plug once and it definitely caused problems in POI changes. Maybe I'll shoot with it torqued to 120 inch pounds instead of 14 foot pounds or so.

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Originally Posted by MuppetMeat4Me View Post
I'm not the least bit qualified to speculate, but generally speaking, when things heat up, the stuff gets looser, unless there's actually residue inside the system that's getting tacky when hot.

Do you think maybe the heat, combined with the gas plug torquing the gas cylinder lock due to excessive play might be pulling an edge up and scraping the piston?

Is it all smooth on the inside, visually and to touch?

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Old March 20th, 2017, 11:02 PM   #24
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Originally Posted by gettinolder View Post
Interesting, my piston test when actively shooting between shot strings is very sticky and does not slide easily, maybe with shaking the rifle, as opposed to when things are cooled off.

I see no residue or fouling in cylinder, nor any roughness.

What you suggest about gas plug torque possibly causing binding because of gas lock 'play' is intriguing, I know I overtorqued the plug once and it definitely caused problems in POI changes. Maybe I'll shoot with it torqued to 120 inch pounds instead of 14 foot pounds or so.
Just a guess, but if that makes any difference, maybe try shims to get you about just short of 6:00 before you get any resistance?

I'm really just shooting in the dark. But, if the gas cylinder lock is not tight until 8:00, and you back it off to 6:00, and then tighten it, it will apply torque between the lock and the cylinder. As things heat up under stress, they might slightly move...

I'm interested in what somebody who knows might think.

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Old March 21st, 2017, 12:25 AM   #25
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Originally Posted by gettinolder View Post
Looking at the gas cylinder?

What did you do?
The M-25 vent mod, it goes in the tail of the G/C.

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Old March 21st, 2017, 02:00 AM   #26
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Burrs on interior of gas port from over boring.

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Old March 21st, 2017, 03:40 AM   #27
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Originally Posted by gettinolder View Post
Copious amounts of Hornady 168gr BTHP and Hornady 155 OTM, plus my own loads of 165 gr and 168 gr with 39.5gr of IMR 3031. 50/50.
Those should be fine. Their A-Max loads are on the hot side. The Superformance ones are way too hot.

Is that a factory SAI barrel? Socom gas ports are larger than normal, to compensate for the short barrel, but yours may be even larger than spec.

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Old March 21st, 2017, 08:08 AM   #28
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Criterion from FA last December.

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Originally Posted by KurtC View Post
Those should be fine. Their A-Max loads are on the hot side. The Superformance ones are way too hot.

Is that a factory SAI barrel? Socom gas ports are larger than normal, to compensate for the short barrel, but yours may be even larger than spec.

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Old March 21st, 2017, 08:11 AM   #29
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Thanks, searched the image late last night and found a thread describing it more or less.

Possible then that silica deposits caused the scoring of piston. It also appears that the purging of the system through this modification gets dumped into stock forearm?

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Originally Posted by Phil McGrath View Post
The M-25 vent mod, it goes in the tail of the G/C.

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Old March 21st, 2017, 08:23 AM   #30
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Unitized gas cylinder is one the smith installed before bedding, will give him a call later on today.

He is in process of regaining his strength after a hard fought battle with infection and I pray for his full recovery.

Don't want any of our old time smith/armorers leaving before their time. Thankfully younger guys like Tony and many other members of this forum are picking up the slack and learning the voodoo science.

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Originally Posted by nf1e View Post
Burrs on interior of gas port from over boring.

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