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Discussion Starter · #1 · (Edited)
ETA: I found this out after initial post, posted it here in later pages, but wanted it to be seen first since it invalidates my comments here.

I'm calling the results of my testing invalid. This is what happens when you publish test results without the use of proper, periodic, controls.

Upon removing the TWS gen2 top cover and using my R-1 Aimpoint micro mounted on an Ultimak AND a 4x scope mounted on a siderail mount, I discovered that my SLR-106 is now shooting 5-6 MOA with all ammunition used, including Prvi Partizan 75gr, which used to shoot 2-3 MOA with this rifle. I found that the rifle has extreme throat wear after less than 8000 rounds of mostly cheap Russian ammunition (mostly Brown Bear, with some Occasional Wolf and Ruag steel case). I believe it was prematurely worn by the bi-metal jackets of the ammunition, as I expected at least 20,000 rounds before going beyond 4 MOA. Experiments with custom reloads produced erratic results, the best of which were 5 MOA.

I'll try the test again after I am able to have a replacement barrel machined to size and installed, though that will likely be far into the future.

Lessons learned: 1. Perform PROPER controls (in this case, I should have been SURE it was the optic mount and not the rifle or optic causing poor accuracy) 2. Keep bi-metal jacketed ammunition (THE HELL!) away from any weapons you can't easily/cheaply rebarrel, as it will wear them out 3-4 times faster than copper jacketed ammunition. See the Vuurwapen guy's article on Lucky Gunner where they tested steel case ammo and found out about the additional wear caused by steel jackets. (Now I'm wondering about my Brown Bear 9mm too.)
Over two years of use, I've found that the TWS Gen 2 Dogleg rail suffers from the same issue that all previous AK top cover optic mounts have: shifting zero.

Zero shifts if the top cover is struck, when the top cover is opened and closed, and it also shifts to a lesser extent during firing. It still functions well enough to make good COM hits out to 200 yards, but it degrades the typical 2-3 MOA accuracy of my SLR-106 to as bad as 6 MOA within its 2-4 MOA horizontal, 1-3 MOA vertical, 'diagonal arc of error.'

I found that the front hinge section, which replaces the rear sight, does not fit tightly in between the "ears" on the rear sight block, at least on my example. I believe this is because my rifle is Bulgarian, which I understand have rear sight blocks with wider gaps. This contributed to horizontal shift in zero. I was able to solve this issue after Mr. Fesas suggested adding a shim here. I achieved this by making a "U" shaped shim out of a bent and drilled section of feeler gauge, fitting it around the front hinge section which fits into the rear sight block, using the hinge pin to hold it in position. This reduced my horizontal zero shift, but did not effect the vertical.

Bending the side spring tab further inward to increase its tension seemed to offer another slight reduction in windage shift, but not enough to eliminate it. It had no effect on vertical shift.

After shimming other areas in vain, I finally found the primary culprit: The rear of the cover can twist longitudinally! The camming latch, which replaces the stock rear section of the recoil assembly, cams against the top cover, forcing the rear of it against the top of the rear trunnion. Since it is comparatively narrow and is in the center of the topcover rear, I believe it is not supplying sufficient lateral stability and may not apply enough downward force to prevent the rear of the topcover from being able to twist very slightly. It does apply enough force for friction to prevent the top cover from settling back into it's precise original position each time the weapon is jolted sufficiently, resulting in the TWS Gen 2 Dogleg Rail's inability to reliably hold zero.

I have communicated my findings to the designer, along with an idea for a solution that I hope will at least serve to help illustrate the problem.

This experience has proven educational and has made me wonder about the real abilities of top cover mounted optics in military use, like the Valmet and Galil's rear iron sights, to retain zero and if they do how those designs might be looked to for a solution.

I sincerely hope Mr. Fesas is able to finish the refinement of his TWS rail, as it seems so close to succeeding where everyone else has failed. His is still the lightest and among the most position-flexible optic mounting solutions to date for the Kalashnikov rifle.
 

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One detail that is important, what optic are you using? If you are using a variable or heavy bodied scope I can see the issues. If you are using a lightweight red dot or holographic optic like I have used on many TWS rails, I doubt you would see such an issue as stated above.
I also have used the TWS system on several different rifles and with red dot or holographic optics I have had no noticeable POI shift after shooting, opening, or otherwise using the TWS rail.
 

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thanks for the write-up. Honestly, i am not surprised. I remember certain people writing articles stating that they have been using this product on their PSLs and gotten consistent hits at VERY far distances using a good optic and TWS rail. year right. LOL

the only duscover with permanately attached peep sight that held zero was Krebs 6,5 Grendel. That I have handled. I do have a new m76 Valmet with similar setup, but i have not had time to mess around with it yet.
 

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Dissapointing. Thank You for the write up.
 

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Discussion Starter · #6 ·
One detail that is important, what optic are you using? If you are using a variable or heavy bodied scope I can see the issues. If you are using a lightweight red dot or holographic optic like I have used on many TWS rails, I doubt you would see such an issue as stated above.
I also have used the TWS system on several different rifles and with red dot or holographic optics I have had no noticeable POI shift after shooting, opening, or otherwise using the TWS rail.
I used an Aimpoint R-1 mounted just in front of the rear peep sight.

I found that there was a sort of Gaussian curve effect, with most of the rounds still striking close to the original point of aim, but the overall extreme spread opened up and the whole group would shift around 4 MOA on average whenever the cover was opened and then closed again.

I'm truly disappointed. I really liked that the rail added no weight and allowed me to put my 3.7oz optic all the way to the rear, which helped offset the weight of a flashlight and suppressor. I liked that with the rail, my AK weighed the same as a SCAR16s. I even liked the way it looked.

I think the TWS cover could still be made to work if the rear cam were made 3x wider and used the greater force of a quick-detach-style (or Russian sidemount type) lever instead of the recoil spring. I also think it would be wise to do something similar in the horizontal plane and eliminate the spring tab entirely. The issues with variable fit at the front hinge could be handled using some steel wedges built into the front of the cover that could repeatably locate it against the rear sight block as the cover was rotated downward to close.

I tried everything I could think of to make this rail work, and short of a redesign, it just can't. I may throw it on again and rig something up to use a squeeze clamp to firmly hold the cover to the rear trunnion to test my theory, but for now it's back to the Ultimak for for my R-1. I'll probably also try swapping out my Surefire g2 LED for something lighter to try and offset the balance difference.

P.S. Finding out a cheaper, softer type of aluminum than mil standard was used in it's construction and knowing now what I do about Gabe Suarez' operation (I bought mine from One Source Tactical), I can't help feeling like the product may have been more money-centric than end-user focused from its inception. It seems when products created primarily to make money succeed in actual use, it's by coincidence.
 

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Discussion Starter · #7 ·
I also have one concern that I will ask here in case someone else might also have the same concern. I know that the side the side rail on my AK is not parallel to the top of the receiver. It's close, but still several millimetres too high in the front. Any reason this would exclude the use of a side rail mount?
Thanks.
The answer is "maybe." AK side rails are fitted by hand and aren't perfectly aligned. In my experience, it usually isn't off by enough to prevent an optic from being zeroed. The only way to know for sure is to try it.
 

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Belloc- can you take a picture of your side mount?

several mm seems a bit high. I have examined some of my AKs in the last 10 minutes- both my homemade kits and factory rifles, all of the have the rails pretty much parallel to the top of the receiver. And all of them have used some kind of side mount with scopes on them succesfully.
 

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Belloc- can you take a picture of your side mount?

several mm seems a bit high. I have examined some of my AKs in the last 10 minutes- both my homemade kits and factory rifles, all of the have the rails pretty much parallel to the top of the receiver. And all of them have used some kind of side mount with scopes on them succesfully.
Sure.
 

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who built the rifle if you dont mind me asking?

the rail definetly sits too high anteriorly.

if you extrapolate even a mm and a half out to 100 meters you will see that you might run out of vertical elevation adjustment.

have you tried to scope the rifle yet?
 

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i had a chance at lunch to take some quick pix- for ya
factory Molot

factory Cugir

factory Izhmash


factory Bulgarian



some of the my hackjob builds
bulgy

Russian


looks like for the most part they are all parallel with the top of the receiver

you are in Maryland? how far from PA border....maybe we can give you a hand with the rail. depending how it was drilled, there is a few not-so diffilcult solutions that could be used to solve rail alingment. AND. that chinese rail is the best one either....i got a few in my basement, i think i even have a few of Doug Fords Russian pattern rails...
 

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Discussion Starter · #12 ·
No problem. Glad you got some good info and I hope you get your rail squared away. :)

Is it odd I've started having dreams about fixing the TWS top cover?
 

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originally i thought you had more of a standard rail (see the pix above) and if one side was slightly off- in your case the anterior, you could have punched that rivet out and inspected the hole. Perhaps the rivet was pressed on at an angle, and often enough you can re-do it correctly.

in your actual case i would get rid of that rail all together. I found my extra rail in the basement, and i can sell/trade it to you for something. I think it was 25$ years ago.

I would do the job correctly. take the old rail out, weld up the holes and drill/rivet new rail. I know it is a bit of work, but its the right approach. Contact Matt- turbothis. he is quick, reliable and VERY well priced if you want it done ina jiffy
 

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Discussion Starter · #14 ·
I'm calling the results of my testing invalid. This is what happens when you publish test results without the use of proper, periodic, controls.

Upon removing the TWS gen2 top cover and using my R-1 Aimpoint micro mounted on an Ultimak AND a 4x scope mounted on a siderail mount, I discovered that my SLR-106 is now shooting 5-6 MOA with all ammunition used, including Prvi Partizan 75gr, which used to shoot 2-3 MOA with this rifle. I found that the rifle has extreme throat wear after less than 8000 rounds of mostly cheap Russian ammunition (mostly Brown Bear, with some Occasional Wolf and Ruag steel case). I believe it was prematurely worn by the bi-metal jackets of the ammunition, as I expected at least 20,000 rounds before going beyond 4 MOA. Experiments with custom reloads produced erratic results, the best of which were 5 MOA.

I'll try the test again after I am able to have a replacement barrel machined to size and installed, though that will likely be far into the future.

Lessons learned: 1. Perform PROPER controls (in this case, I should have been SURE it was the optic mount and not the rifle or optic causing poor accuracy) 2. Keep bi-metal jacketed ammunition (THE HELL!) away from any weapons you can't easily/cheaply rebarrel, as it will wear them out 3-4 times faster than copper jacketed ammunition. See the Vuurwapen guy's article on Lucky Gunner where they tested steel case ammo and found out about the additional wear caused by steel jackets. (Now I'm wondering about my Brown Bear 9mm too.)
 

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Appreciate you showing what caused the problem. Rare to see someone stand up and admit they're wrong. I'm around several engineering and various science majors on campus; most will not admit they made a mistake when doing research.

Definitely will have to look into bi-metal jacketed ammo. What brands does this include?
 

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I'm experiencing the rear of my dogleg shifting laterally. I can take my finger and move it, and watch the red dot move off to the side. I have to move the rail back to get the red dot to center. Not too happy about it. I really had high hopes for this... I think the space between the spring "button" and the top cover is too wide, allowing too much movement. I'm searching for a fix, but am slowly starting to consider the ultimak.
 

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I'm experiencing the rear of my dogleg shifting laterally. I can take my finger and move it, and watch the red dot move off to the side. I have to move the rail back to get the red dot to center. Not too happy about it. I really had high hopes for this... I think the space between the spring "button" and the top cover is too wide, allowing too much movement. I'm searching for a fix, but am slowly starting to consider the ultimak.
Wouldn't be hard to fix that. Weld or use a little JB Weld and build up the button on the left side and then file it down until it fits just right. The "spring" tension from the right side of the cover should keep it nice and tight.
 

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i guess i have a stupid question...why not use something that has been battle proven for nearly 70 years? - a side rail? why go through all this trouble with replacing FACTORY parts,
when all you need is a decent side mount?

RS regulate makes bunch of different styles if you cant get the original Russian parts, it sits low, you got you cowitness....
is it because you dont have a side rail on your AK?


I'm experiencing the rear of my dogleg shifting laterally. I can take my finger and move it, and watch the red dot move off to the side. I have to move the rail back to get the red dot to center. Not too happy about it. I really had high hopes for this... I think the space between the spring "button" and the top cover is too wide, allowing too much movement. I'm searching for a fix, but am slowly starting to consider the ultimak.
 

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i guess i have a stupid question...why not use something that has been battle proven for nearly 70 years? - a side rail? why go through all this trouble with replacing FACTORY parts,
when all you need is a decent side mount?

RS regulate makes bunch of different styles if you cant get the original Russian parts, it sits low, you got you cowitness....
is it because you dont have a side rail on your AK?
.

A stupid Question deserves a smart answer -- there is no real reason. In my experience you can't get a better result than an optic mounted on a side rail on the AK platform. As long as there is nothing wrong with the rail and your optic / mount is capable of holding zero that is. The only bad experience I had was with the side rail on an early VEPR 308 would group under 2" @100yds with a 4x PSO. Any larger higher mag scopes wouldn't group worth crap (never tried a higher mag pso / posp). Finally realized there might be a problem with the rail -- only 2 rivets held it on. So I drilled and tapped the center of the rail and ran a button head screw inside to out. Never tested to see if it was fixed or if it was really a problem. I think the issue was more optic related. Currently I'm running a TWS Dogleg Beta Test unit which I custom fit to the RPK receiver. It is tight with no flex whatsoever. But I'm limited to a light scope currently One of Primary Arms 1-6x. If I ever needed more magnification I'd switch back to the side rail. Definitely don't trust the TWS with a really heavy optic. Probably use an RS mount but would probably try an MI Picatinny mount first.

So in summary the side rail is the first answer and the best answer. Also it doesn't screw up the clean AK lines:inquisition:
 
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