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Tac-47 Autoplug Mod Question


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My thought was to add another small hole just a little forward of the first row,  so that it can vent faster progressively. A shoulder on the poppet valve could give it two different working diameters too, so that if it opened up further, the larger diameter would be exposed and cause it to open more yet.


Were you aware of the basic mod I did? http://forum.saiga-12.com/index.php?/gallery/album/1219-tac47-autoplug-gf-magnum-edition-mark-15/ 

 

Not automatic, but it covers the very hottest 3" magnums nicely.

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He's asking if you can enlarge the vents so you can run 3" magnums without damage.

Not needed. Simply turn 90 degrees to restrict gas flow through the gas block, diverting it out the muzzle.

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He's asking if you can enlarge the vents so you can run 3" magnums without damage.

Not needed. Simply turn 90 degrees to restrict gas flow through the gas block, diverting it out the muzzle.

 

 

Works with some brands of magnums and not others. May vary from gun to gun. Hence my mod.

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He's asking if you can enlarge the vents so you can run 3" magnums without damage.

 

Not needed. Simply turn 90 degrees to restrict gas flow through the gas block, diverting it out the muzzle.

 

Works with some brands of magnums and not others. May vary from gun to gun. Hence my mod.

You could also include how someone shoulders their gun.

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GunFun, I saw your mod, and tried a variation of it. I ran a 1/8 ball mill across the back end to make a second notch about .100" deep. It works, but when I have the screw adjusted to eject low brass about 3-4' in the normal (big notch) setting, some 3" magnums still eject 15-20' with the high (small notch) setting. Another consideration is that in the high setting, the vent gas is bieng directed down when that is the last thing you want recoil-wise. I replicated the factory hole pattern in the 4- and 8-oclock slots, and enlaged all the holes from about .154 to .165".

If that shows signs of improvement, I'll probably convert all the holes to 3/16" wide slots, and maybe bore out the poppet valve seat. The valve itself is almost twice as big as the hole it covers; i don't see why you couldn't increase the hole to 75-85% of the valve diameter as long as you open up the exit vents to match.

Edited by JonWienke
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GunFun, I saw your mod, and tried a variation of it. I ran a 1/8 ball mill across the back end to make a second notch about .100" deep. It works, but when I have the screw adjusted to eject low brass about 3-4' in the normal (big notch) setting, some 3" magnums still eject 15-20' with the high (small notch) setting. Another consideration is that in the high setting, the vent gas is bieng directed down when that is the last thing you want recoil-wise. I replicated the factory hole pattern in the 4- and 8-oclock slots, and enlaged all the holes from about .154 to .165".

 

If that shows signs of improvement, I'll probably convert all the holes to 3/16" wide slots, and maybe bore out the poppet valve seat. The valve itself is almost twice as big as the hole it covers; i don't see why you couldn't increase the hole to 75-85% of the valve diameter as long as you open up the exit vents to match.

 

I would have used a mill if I had one. 

 

I don't think there is enough gas flow or pressure happening to make any meaningful thrust. I am not worried about the orientation of the vents on the autoplug at all.

 

Keep us informed on what your slots do. Enlarging the holes by drilling up would make them start working earlier too. I am not sure that's something I would want, but I could see larger holes or slots moving toward the muzzle end of the plug be a good idea.

 

Yeah, but I always want the gun to run regardless of how it is held.

 

 

We certainly agree on that!

 

 

Since it is easily achievable (outside of some SBSs with light ammo), I've never heard a compelling argument not to have that level of reliability. 

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I'm not super concerned about the recoil compensation aspect of the vent gas, but it did peel some of the paint off the barrel next to the vent holes. Adding additional holes pointing away from the barrel should reduce that.

 

Enlarging the holes isn't going to make the plug start working "earlier"--once the valve is pushed away from the seat by gas pressure, gas can start flowing around it into the spring cavity, regardless of the exact location of the vent holes. The valve seals to the seat at the rear of the regulator, but not to the sides of the spring cavity. My intent is to reduce the pressure buildup in the spring cavity so that the input/output pressure curve in the gas block is flatter above the regulator break-open pressure.

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I tried it out today, and it worked pretty much as I'd hoped. I ran every high brass load from cheap 2.75" Estate buckshot and Winchester and Remington #1 buck to 3" Federal magnums and ejection was between 5 and 12 feet, without changing any settings on the gun. Opening up the exit ports flattens the regulator pressure curve above the set point so that 3" magnums are closer to standard 2.75" shells in cycling/ejection energy.

 

My modified regulator has 8 .165" holes now, 2 in each slot.

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I tried it out today, and it worked pretty much as I'd hoped. I ran every high brass load from cheap 2.75" Estate buckshot and Winchester and Remington #1 buck to 3" Federal magnums and ejection was between 5 and 12 feet, without changing any settings on the gun. Opening up the exit ports flattens the regulator pressure curve above the set point so that 3" magnums are closer to standard 2.75" shells in cycling/ejection energy.

 

My modified regulator has 8 .165" holes now, 2 in each slot.

Pictures please. I am looking at Gun Fun's work and it would be great to see this. I'd love it if I could use an autoplug reliably for everything you can feed a Saiga 12.

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I tried it out today, and it worked pretty much as I'd hoped. I ran every high brass load from cheap 2.75" Estate buckshot and Winchester and Remington #1 buck to 3" Federal magnums and ejection was between 5 and 12 feet, without changing any settings on the gun. Opening up the exit ports flattens the regulator pressure curve above the set point so that 3" magnums are closer to standard 2.75" shells in cycling/ejection energy.

 

My modified regulator has 8 .165" holes now, 2 in each slot.

Pictures please. I am looking at Gun Fun's work and it would be great to see this. I'd love it if I could use an autoplug reliably for everything you can feed a Saiga 12.

 

 

 

You can, but make your gun run 100% without the Autoplug first. Then try the Autoplug without modifying it. 

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What if the gun cycles high brass like candy but cheap wally world bulk pack stuff jams and doesn't cycle? Would this thing help? I was going to get an mdarms vplug bc I know it has more settings but every where is sold out. One of the vplug settings I know for a fact will let more gas in than what the factory plug does on setting 2 right now and that may just be what I need...

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 I was going to get an mdarms vplug bc I know it has more settings but every where is sold out. One of the vplug settings I know for a fact will let more gas in than what the factory plug does on setting 2 right now and that may just be what I need...

 

This is wrong. There is a maximum amount of gas created by a given cartridge. #2 on the factory plug allows the maximum amount of gas into the gas system. The highest setting on the V-plug does not increase that, but the lower settings of the V-plug reduce the allowed gas by varying amounts, rather than open or close as with the factory plug.

 

It sounds to me like your gun is under-gassed.

Edited by YOT
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