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SA Unitized GC, pics

This is a discussion on SA Unitized GC, pics within the Accuracy forums, part of the M14 M1A Forum category; Originally Posted by KurtC Check with folks like Lysander et al regarding modifying the dwell. The only way I know of to do that is ...


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Old December 18th, 2016, 06:41 PM   #16
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Quote:
Originally Posted by KurtC View Post
Check with folks like Lysander et al regarding modifying the dwell. The only way I know of to do that is to shorten the piston tail. That will require a re-heat or possibly nitride. You have to be careful that you are not letting forward movement of the oprod stop on the bolt roller or oprod guide.
Think I'll skip that one!!!!

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Old December 18th, 2016, 07:58 PM   #17
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Originally Posted by KurtC View Post
You don't tighten a unitized gas cylinder against the barrel shoulder. The idea is to have the gas lock pull the unit forward, away from the barrel shoulder. When you position the gas lock at 6 o'clock, you tap the unitized gas cylinder forward against the lock and insert the plug.
It's part of the National Match mods which I have researched and done to my rifle.

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Old December 18th, 2016, 08:10 PM   #18
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Originally Posted by WalnutScout View Post
It's part of the National Match mods which I have researched and done to my rifle.
I have the SAI unitized GC on my JRA DMR21 Build and have had non of the problems you speak of. I have done the National Match mods.

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Old December 18th, 2016, 08:32 PM   #19
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Originally Posted by WalnutScout View Post
It's part of the National Match mods which I have researched and done to my rifle.
I know of no factory National Match rifle that comes with shims. They are a product of internet lore. The idea is to free float the barrel as much as possible. Shims, and tightening the unitized gas cylinder against the barrel shoulder, have the opposite effect.

See V and W in the below illustration:


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Old December 18th, 2016, 09:21 PM   #20
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When I was considering what to do - to unitize or to shim - my upper band, I found the excellent information in this old thread very helpful:

Unitizing in Isolation

I suggest a thorough read. The rifle that I was working with was not bedded and I went with shims. There was a positive improvement in accuracy.

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Old December 19th, 2016, 09:25 AM   #21
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Thanks, JWolfe. Somehow, I missed your treatise from 2012.

I am torn between J's philosophy and GusF's practice ( and USMC TM) of shimming every rifle, even though unitized.

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Old December 19th, 2016, 09:42 AM   #22
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Originally Posted by KurtC View Post
You don't tighten a unitized gas cylinder against the barrel shoulder. The idea is to have the gas lock pull the unit forward, away from the barrel shoulder. When you position the gas lock at 6 o'clock, you tap the unitized gas cylinder forward against the lock and insert the plug.

Yep -that's the original USAMTU specified procedure and stills work well today.

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Old December 19th, 2016, 10:58 AM   #23
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Quote:
Originally Posted by DudleyDR View Post
When I was considering what to do - to unitize or to shim - my upper band, I found the excellent information in this old thread very helpful:

Unitizing in Isolation

I suggest a thorough read. The rifle that I was working with was not bedded and I went with shims. There was a positive improvement in accuracy.
I also shimmed my M1A loaded, and consistency dramatically improved.

I was warned about the alignment problem, on another thread, regarding a prefabbed unitized GC aligning with the stock ferrule. For $100, I figured I'd give it a try. If it makes things worse, I'll go back to the shims.

I also figured I'd have a better chance of a proper fit with the SA GC, rather than the Fulton Armory unitized GC, which does look to be more robust, and is also twice the $$.

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Old December 19th, 2016, 11:43 AM   #24
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Quote:
Originally Posted by ColdWarPigGnR View Post
I also shimmed my M1A loaded, and consistency dramatically improved.

I was warned about the alignment problem, on another thread, regarding a prefabbed unitized GC aligning with the stock ferrule. For $100, I figured I'd give it a try. If it makes things worse, I'll go back to the shims.

I also figured I'd have a better chance of a proper fit with the SA GC, rather than the Fulton Armory unitized GC, which does look to be more robust, and is also twice the $$.
When I first shimmed my loaded, it improved my accuracy. Not a dramatic change but a perceived improvement if maybe 1/4 moa.
Or so I thought until I removed them 6 months later and saw no decrease in accuracy.

Draw your own conclusions but I believe in my haste of trying to do somethings to improve it quickly, it just took stick time.m of getting comfortable with a new platform.

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Old December 19th, 2016, 12:38 PM   #25
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In my case, I had no choice but to shim.

Once I relieved the stock from contact with the GC and op rod guide, the front band was able to move about.

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Old December 19th, 2016, 05:05 PM   #26
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Installed.............

Frontband is a little forward of its previous shimmed position, which timed @ 530.(Pic #3 shows this clearly)
Also, before relieving the stock and hand guard , the front band was very tight on the ferrule, nothing moved. I'm guessing thats what the wear on the ferrule is from......

I tightened the gas lock to 600, then tapped the GC forward. (Thanks KurtC)

Feeler gauge put the distance from ferrule to frontband @ .025"

Range day...... who knows when?!?!?
Attached Images
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File Type: jpg IMG_3023.jpg (33.9 KB, 19 views)
File Type: jpg IMG_3022.jpg (31.8 KB, 19 views)
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Last edited by ColdWarPigGnR; December 19th, 2016 at 05:18 PM.
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Old December 20th, 2016, 06:29 AM   #27
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Quote:
Originally Posted by KurtC View Post
You don't tighten a unitized gas cylinder against the barrel shoulder. The idea is to have the gas lock pull the unit forward, away from the barrel shoulder. When you position the gas lock at 6 o'clock, you tap the unitized gas cylinder forward against the lock and insert the plug.
My gas lock times out tight at six-o-clock and my unitized cylinder is tight against the barrel shoulder, should i back it off one complete turn? Then tap my cylinder forward against that?

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Old December 20th, 2016, 07:40 AM   #28
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Originally Posted by six clicks View Post
My gas lock times out tight at six-o-clock and my unitized cylinder is tight against the barrel shoulder, should i back it off one complete turn? Then tap my cylinder forward against that?
I'm no expert six, but that would be a real easy fix to try. If accuracy sucks, it's easy to go back to your old setup.

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Old December 20th, 2016, 07:47 AM   #29
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looks laser welded

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Old December 20th, 2016, 08:33 AM   #30
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Gas port alignment?

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