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Discussion Starter · #1 ·
Hi All... The other day I ordered me one of them and it has arrived... I have a 2006 SAI SM that shoots a couple loads pretty well from what I know.

Any advantage to installing this? Experience's? Advantages? Disadvantages?
 

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I use a grooved Sadlak piston in my M25.

The theory, from an accuracy standpoint, is that a grooved piston slows down the action, thus increasing the "dwell time" (search that one and have fun!) which improves accuracy.

The more practical application is that it vents excess pressure when using heavier bullets, thus reducing the amount of stress that is put on the operating rod and the bolt by slowing down the action.

I've used mine with 125's to 178's without any function issues.

Tony.
 

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Discussion Starter · #4 ·
I use a grooved Sadlak piston in my M25.

The theory, from an accuracy standpoint, is that a grooved piston slows down the action, thus increasing the "dwell time" (search that one and have fun!) which improves accuracy.

The more practical application is that it vents excess pressure when using heavier bullets, thus reducing the amount of stress that is put on the operating rod and the bolt by slowing down the action.

I've used mine with 125's to 178's without any function issues.

Tony.
Thanks Tony. I have not installed mine yet but intend this summer/fall to crono my 'ten dot' loads and think I will need to 'load up' some... The one 'ten dot' load shoots very well at 400 meters though; need to check the other...
 

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Me too. Especially the way it dumps the brass in a nice neat pile at my right elbow instead of at one o'clock and having to wait for a line-break to police up my brass! -Lloyd BEERCHUG1
 

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Thanks Tony. I have not installed mine yet but intend this summer/fall to crono my 'ten dot' loads and think I will need to 'load up' some... The one 'ten dot' load shoots very well at 400 meters though; need to check the other...
Me too. Especially the way it dumps the brass in a nice neat pile at my right elbow instead of at one o'clock and having to wait for a line-break to police up my brass! -Lloyd BEERCHUG1
Gents, what lot number are your pistons?
 

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I'd have to dig around my gun paperwork, but I can tell you that I bought and installed it in Oct.,2014. The barrel is a Wolfe, Modified Standard Weight Match, 1-10 twist. -Lloyd BEERCHUG1
 

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Piston #

I bought, and installed, my grooved Sadlak titanium coated piston a couple of months ago. Works great!
 

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Is it a noticeable improvement in accuracy or primarily for reduction in effects of bullet weight/pressures?
And if it is an accuracy improvement, is it over the full spectrum of bullet weights?

edit: I know what Sadlak has to say. What is the real world scenario.
 

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Is it a noticeable improvement in accuracy or primarily for reduction in effects of bullet weight/pressures?
And if it is an accuracy improvement, is it over the full spectrum of bullet weights?
Everyone's rifle will be different and you'll just have to try it on your rifle. Gas pistons are funny. You can get two identical pistons and install them in the same rifle and get different results. Some guys keep a pile of pistons to try with their rifles and go with the one that yields the best accuracy.

Tony.
 

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Improved accuracy?

Is it a noticeable improvement in accuracy or primarily for reduction in effects of bullet weight/pressures?
And if it is an accuracy improvement, is it over the full spectrum of bullet weights?

edit: I know what Sadlak has to say. What is the real world scenario.
I experienced improved accuracy, but I switched ammo at the same time, so I can't say it was the piston. I switched from FGMM to Lapua 168s. The Lapua rounds display a marked improvement in my rifle when compared to the FGMM.
 

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Godspeed Greyson
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Everyone's rifle will be different and you'll just have to try it on your rifle. Gas pistons are funny. You can get two identical pistons and install them in the same rifle and get different results. Some guys keep a pile of pistons to try with their rifles and go with the one that yields the best accuracy.

Tony.
Thanks Tony. I understand the situation with pistons in general. I was just wondering if the different design/function resulted in inherent accuracy improvement. GI2
 

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Is it a noticeable improvement in accuracy or primarily for reduction in effects of bullet weight/pressures?
And if it is an accuracy improvement, is it over the full spectrum of bullet weights?

edit: I know what Sadlak has to say. What is the real world scenario.
The piston is supposed too keep the barrel from flexing up and down from each venting of the gas cylinder and it does do that. However, I can tell you this, I've used my grooved TiN piston with everything from 125-185's weight bullets. Did I see a accuracy gain or improvement in my rifles from the bench or position.... Kind of sorta, but more importantly I didn't see it degrade either, what did change and was most feelable was the recoil impulse. The rifle has a softer straight push too the rear, instead of the normal bang and jab too the rear and the muzzle climbs up. Overall I would say it made the shooter more comfortable while the muzzle is pointed at the target still, my score's went up as the result of the better follow through.

That's the best I can describe the benefits/behavior of the grooved pistol, I know that recoil impulse is also subjective between different shooters, what I feel isn't the same as what you feel.

My piston is a early one from there 2nd run and its been in a few rifles over the years. Heavy, med, std. weight barrels and all behaved the same in each one the most dramatic difference for the better was with the GI contour barrel. So in a nut shell I say they work well.
 

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Early testing with my Scout Squad at 100 yards and Iron sights suggested the non-grooved piston performed better when using Fed 168 GMM. Way better!

The non-grooved NM piston = 1 MOA, the Grooved NM piston = 4+ MOA

Of course, different gun, different ammo, different shooter..........different results.

YMMV!
That doesn't surprise me, the Scout/Bush barrels being shorter.
 

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While Im not surprised either, this gun has been a struggle to tame. Walk us through the science of why the groove doesnt work as well with a shorter barrel? Please!

Thanks.
With the bullet leaving the barrel sooner, there is less pressure going into the gas cylinder, making the groove less effective.

This is why Socom barrel gas ports are larger than standard barrel gas ports.
 
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