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Puck Install Question

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New Owner of Lynx12, love the Saiga style gun.  Fun to shoot!!!  Cycles everything so far, have had fun varminting at night!

I purchased a Carolina Shooters Gas Puck.  Should the flat face with "CSS USA" or the face with the raised center be interfacing the Rod/Action?

Their website says one end should face "forward" but I'm not sure which end of the gun is "forward" per se.

Also, I purchased 2 Lynx 12s (one as gift). Got great deal at Brownells. I purchased 2 Carolina pucks.  One puck measured slightly smaller in diameter than the other, and definitely moves around easier in the gas block than the other (in both guns). One was 21mm and the other 20 and change.... is one preferred over the other? ( Tighter fit vs looser fit better)?  Also, edges of Carolina puck sharp corners vs stock, relieving edge w rol-loc any easier for wear?

The Carolina pucks were 13.6mm long from seat to Rod interface vs. 13.5 on the unit that came in the gun.  Both Carolina pucks were same 13.6....but definite variance in diameter. I didn't measure gas block ID....I can do that.

Lynx barrel bores were both .730" at muzzle, both SGM Mod chokes were .710" at muzzle for .020" reduction; consistency there.

Just checking things out.  Anyhow, thanks for info and expertise!



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So Carolina ( thanks Carolina!) put it in terms I understand:

Puck nipple (raised end) points the direction you are aiming (or faces the gas adjuster cap).  That leaves the flat face with "CSS USA" to interface with the action/Rod.

I've seen two videos where the CSS puck is installed wrong, the opposite of their instruction.

Ive heard the "front" of the gun identified as both the shooter/operators end as well as the muzzle end now on the net.

Which is truly correct??  This is why I asked for install instruction in terms of barrel end/muzzle vs buttstock or operator end.

Anywho, anyone have 2 cents on puck size issue?


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Over thinking it. Bullets come out of the FRONT!  The new free piston works or does not. Try it and see, it is not rocket science!

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That's what I ASSumed to be correct.  But there's misinformation out there (2 vids) and alternate definitions of "front" of a gun.

 It is science actually, developed by people called engineers, they design things to "specs."  

You can half ass it and go by guess work, I'll measure and record so I then know what worked and why.

CS puck likely end up in trash.


Edited by Saiga12Newb

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So I initially thought the lil nub  was for minimally interfering (friction, hydro lock, lessening gas effectiveness) but I think really if it is pointed the other way what the cup does is increase the surface area of the face where the gas can act. So if you are dealing with limited port size only way to increase the “work” done by the gas that you have in the chamber is to increase the “force” of the work... think my physics terms are a lil mussed up hence the quotations, but the general idea is more surface area for gas to affect = harder push on op rod which translates to more bolt velocity meaning higher reliability. 


Other point  of concern is whether your Chinese clone will work with us parts. 


Also, gas blocks and tubes binding creates some tension that does somethin to the system. Think I dealing with that on a 20 ga right meow

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Good info, I enjoy concepts in hi-po engines like flame propagation etc.  surface area thing makes sense.  That's good stuff.

In another post I read where a member suggested welding up the second largest opening of the gas adjuster on a DPH style adjuster (which my SDS looks exactly like) because " it doesn't cover any more of the holes than the next size" and therefore doesn't reduce the gas pressure at all.

This is errant thinking.  The angle of cut and larger size opening above the gas ports creates a Nozzle in the block, producing thrust on the puck by the expanding gas.  In the following math, area A may be fixed, Area Exit is variable by the Adjuster setting, changing thrust on puck/chamber, and block chamber fill rate.


Welding and tinkering to put a thumb over a garden hose end approach is guesswork at best.  What tooling and scopes are needed to align that welded thumb over the hole to change Area A in the formula above some precise amount? 

Engineers do things for reasons, I'm sure the SDS and DPH units have engineering behind them.

I'll try the Carolina Puck, the stock style has worked fine though all loads, just trying to put some US parts on it, if my gun doesn't like it no big deal.

FWIW, the Chinese clone hasn't required any file fitting of CSS Specs or any other mags, new stock and foregrips have fit like a glove as well, just a light tap w rubber mallet and things are going together great.

Ive seen plenty of knuckleheads try to outsmart factory engineers in quarter mile motors, just to waste money, go slower, and have higher failure rates.

Same can happen in this arena.

I came to this forum to learn what works and why, vs. luck of the draw.

Based on gas block bore size, I'm sure there is an optimal clearance between block wall and puck ( puck size) to mate with it.

Guys with worn guns, or guns made with wide variances in spec could benefit from alternate puck diameters being offered.

Or they could try things hit or miss 100x, cuz it either works or it don't. 

Lynx12 gas block bore measures 21mm

Factory Puck 20.98

Carolina Puck 20.94  

Edited by Saiga12Newb
Add dimensions

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Nomenclature ALWAYS lists front, rear, left, and right sides of a gun. No matter which way the gun is held or lain the labels are still fixed on those sides and ends. It's very elementary and constant.


The little nub in the puck faces front, toward the plug. The concept is to increase the volume inside the the gas block to allow more gas surge to push the puck rearward.

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