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Author Topic: Stronger recoil spring for suppressed Tavor  (Read 2665 times)
AZ-Chris
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« Reply #20 on: August 30, 2017, 11:22:09 AM »

The result I hope to see is exactly what Art just described . . . slowing the speed of the bolt action cycling.  When I shoot my Tavor SAR with either my 30 cal cans (Rugged Surge & Razor) or my 5.56 GemTech Trek, I will occasionally experience a failure to eject.  The spent case just cant get out of the way fast enough and are dented/deformed by the new round being fed.

I personally don't feel the gas issues with the Tavor are any worse than with my ARs . . . that is to say, it's not pleasant, but not a show stopper.
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blottogg
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« Reply #21 on: August 30, 2017, 12:41:52 PM »

Shooting with a Gemtech Halo, the bolt velocity is definitely faster, but I haven't noticed a bigger "thump" at the end of the bolt travel.  I've accommodated the higher velocity by removing the brass deflector to prevent brass re-ingestion, but haven't noticed any damage or additional wear in over 1000 rounds of suppressed shooting.  I have noticed a much stronger blast of gas out the ejection port when shooting cross-shoulder.  The Tavor piston design is double diameter, so the high pressure initial push acts on the small diameter front of the piston, and as pressure drops during backwards travel the second, larger diameter portion of the piston is exposed.  When suppressed, the gas pressure acting on the larger portion of the piston is higher, and counteracting that is where this spring might be useful.  At the end of the piston travel, it actually clears the cylinder, venting any remaining pressurized gas into the receiver (and your face if shooting cross-shoulder).  It's a simple (and less expensive, though messier) way of mitigating over-pressure in a non-adjustable system, and is probably why I haven't seen any damage to moving bits after all the suppressed firing, or felt the bolt slamming against the fully compressed spring.  Or maybe I just haven't been paying attention.

I like the idea of having a stiffer recoil spring available for tuning with a suppressor, but for the moment I don't see the need, at least for the combination of hardware I'm currently running on my gun.
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RabbitSlayer
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« Reply #22 on: August 30, 2017, 04:15:14 PM »

I think you'll find stronger recoil springs will do little to nothing to keep the bolt closed longer or reduce gas. Search for George M. Chinn's firearms design books on the net for enlightenment.

Lol wut?

Stiffer recoil springs increase the time it takes for the action to cycle, stiffer recoil springs slow the cyclic rate of the bolt.  In fact, even guys who shoot suppressed handguns benefit from heavier recoil springs, because it reduces pop near the action, which means less gas is hitting the air by the breach.

Science bro.  This is well documented.


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RabbitSlayer
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« Reply #23 on: August 30, 2017, 04:35:26 PM »

Shooting with a Gemtech Halo, the bolt velocity is definitely faster, but I haven't noticed a bigger "thump" at the end of the bolt travel.  I've accommodated the higher velocity by removing the brass deflector to prevent brass re-ingestion, but haven't noticed any damage or additional wear in over 1000 rounds of suppressed shooting.  I have noticed a much stronger blast of gas out the ejection port when shooting cross-shoulder.  The Tavor piston design is double diameter, so the high pressure initial push acts on the small diameter front of the piston, and as pressure drops during backwards travel the second, larger diameter portion of the piston is exposed.  When suppressed, the gas pressure acting on the larger portion of the piston is higher, and counteracting that is where this spring might be useful.  At the end of the piston travel, it actually clears the cylinder, venting any remaining pressurized gas into the receiver (and your face if shooting cross-shoulder).  It's a simple (and less expensive, though messier) way of mitigating over-pressure in a non-adjustable system, and is probably why I haven't seen any damage to moving bits after all the suppressed firing, or felt the bolt slamming against the fully compressed spring.  Or maybe I just haven't been paying attention.

I like the idea of having a stiffer recoil spring available for tuning with a suppressor, but for the moment I don't see the need, at least for the combination of hardware I'm currently running on my gun.

There is an angled shell deflector that deflects brass downwards maybe this would help?


Here it is..  https://www.bullpuparmory.com/product_p/pa-tavx95-shdef.htm

Anyone try this ?

It's only 12 bucks, so if it didn't work one could always take a file to it and try to get the proper angle.
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Hkbeltfed
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« Reply #24 on: August 30, 2017, 09:56:09 PM »

Stiffer recoil springs increase the time it takes for the action to cycle, stiffer recoil springs slow the cyclic rate of the bolt.  In fact, even guys who shoot suppressed handguns benefit from heavier recoil springs, because it reduces pop near the action, which means less gas is hitting the air by the breach.

Science bro.  This is well documented.

My comments were in reference to keep the breech closed longer and reducing gas. Comparing it to handguns with barrels that recoil with the slide is irrelevant. You apparently feel you already know more than George M. Chinn which is funny all by itself considering he wrote volumes on firearms mechanisms and design. My previous comments are "well documented". That said, I'm not here to bicker with you, so carry on.
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RabbitSlayer
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« Reply #25 on: August 30, 2017, 10:57:44 PM »

Stiffer recoil springs increase the time it takes for the action to cycle, stiffer recoil springs slow the cyclic rate of the bolt.  In fact, even guys who shoot suppressed handguns benefit from heavier recoil springs, because it reduces pop near the action, which means less gas is hitting the air by the breach.

Science bro.  This is well documented.

My comments were in reference to keep the breech closed longer and reducing gas. Comparing it to handguns with barrels that recoil with the slide is irrelevant. You apparently feel you already know more than George M. Chinn which is funny all by itself considering he wrote volumes on firearms mechanisms and design. My previous comments are "well documented". That said, I'm not here to bicker with you, so carry on.

I don't need to read volumes of books to comprehend a simple concept.  Instead of telling us to go read a book; why don't you simply explain the solution we are looking for?
If you have a better solution than adjusting recoil spring weight for our Tavors being overgassed when using suppressors, I am sure we would all love to hear it.  BTW, for those of us shooting 556 Tavors, an adjustable gas block is not an option.

Also, I have a hard time seeing how the pistol reference is irrelevant.  Both blowback operated and gas operated firearms actions timing work in direct correlation with the recoil spring weight.  Many people refer to blowback operation as a simplified form of gas operation.
The #1 suggestion people get in regards to having an overgassed firearm is to use a heavier recoil spring/buffer, so I think the most logical route for us here is to at least try a heavier recoil spring.

But by all means, if you have a better idea please ''enlighten'' us.

« Last Edit: August 30, 2017, 11:28:24 PM by RabbitSlayer » Logged

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blottogg
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« Reply #26 on: August 30, 2017, 11:43:36 PM »

There is an angled shell deflector that deflects brass downwards maybe this would help?


Here it is..  https://www.bullpuparmory.com/product_p/pa-tavx95-shdef.htm

Anyone try this ?

It's only 12 bucks, so if it didn't work one could always take a file to it and try to get the proper angle.

I bought one of those (two, actually) and it didn't solve the problem for me.  Then I started grinding down the deflector (thinking I might have to do this is why I bought 2...like you said, they're not expensive) trying to change the angle of the deflector face enough to keep the brass from bouncing back in to the receiver, but that didn't solve the problem, either.  Finally just took off the deflector (and the ejection port surround that the deflector holds in), and haven't had a problem since.  Looking back, a lower back-pressure suppressor solution would have been less of a pain (OSS, or a 7.62mm can), but c'est la guerre.
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RabbitSlayer
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« Reply #27 on: August 31, 2017, 12:33:03 AM »

There is an angled shell deflector that deflects brass downwards maybe this would help?


Here it is..  https://www.bullpuparmory.com/product_p/pa-tavx95-shdef.htm

Anyone try this ?

It's only 12 bucks, so if it didn't work one could always take a file to it and try to get the proper angle.

I bought one of those (two, actually) and it didn't solve the problem for me.  Then I started grinding down the deflector (thinking I might have to do this is why I bought 2...like you said, they're not expensive) trying to change the angle of the deflector face enough to keep the brass from bouncing back in to the receiver, but that didn't solve the problem, either.  Finally just took off the deflector (and the ejection port surround that the deflector holds in), and haven't had a problem since.  Looking back, a lower back-pressure suppressor solution would have been less of a pain (OSS, or a 7.62mm can), but c'est la guerre.

Interesting. Thanks for the feedback.
I'm trying to design a can with .27" baffles that also has reduced back pressure.  I'm thinking maybe an otb design with ports in the blast baffle.
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Hkbeltfed
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« Reply #28 on: August 31, 2017, 06:33:04 AM »

I don't need to read volumes of books to comprehend a simple concept.  Instead of telling us to go read a book; why don't you simply explain the solution we are looking for?
If you have a better solution than adjusting recoil spring weight for our Tavors being overgassed when using suppressors, I am sure we would all love to hear it.  BTW, for those of us shooting 556 Tavors, an adjustable gas block is not an option.

Also, I have a hard time seeing how the pistol reference is irrelevant.  Both blowback operated and gas operated firearms actions timing work in direct correlation with the recoil spring weight.  Many people refer to blowback operation as a simplified form of gas operation.
The #1 suggestion people get in regards to having an overgassed firearm is to use a heavier recoil spring/buffer, so I think the most logical route for us here is to at least try a heavier recoil spring.

But by all means, if you have a better idea please ''enlighten'' us.

I get it, you're a know-it-all and you don't read. That's why this is a waste of time. I'm not suggesting you read volumes. I'm suggesting you refer to facts from an engineer who wrote volumes on firearms mechanisms including all of the science, formulas, and math behind it.

First you're comparing the Tavor to a handgun with a browning action where the barrel recoils with the slide and now you're referring to it as blowback which is incorrect and another type of action. Again, if you don't know the difference between locked breech, a Browning type, and blowback, look it up. That said, if you think blowback is relevant... http://www.orions-hammer.com/blowback/

An excerpt re: blowback: "NOTE: There is one point which requires special clarification at this time.  In many descriptions of blowback actions, it is strongly implied that the driving spring contributes a substantial portion of the resistance which limits acceleration imparted to the bolt by the powder gases.  Actually, this is not so.  Although it is true that the driving spring absorbs the kinetic energy of the recoiling bolt and thus limits the total distance it moves, the resistance of the spring does not have any real effect in the early phase of the cycle of operation.  The bolt acceleration occurs mainly while the powder gas pressures are high and are exerting a force of many thousands of pounds on the bolt.  The driving spring, in order to permit the bolt to open enough to allow feeding, must offer a relatively low resistance.  Although this resistance is sufficient to absorb the bolt energy over the comparatively great distance through which the bolt moves in recoil, it is not great enough to offer significant opposition to the powder gas pressure until the chamber pressure has dropped to a relatively low level well after the projectile has left the muzzle."

The solution you're looking for is an adjustable gas mechanism. The fact that you feel it's not an option is more ignorance in line with you narrow minded, know-it-all thinking in your posts above. Beyond that, its to vent excess gas in a controlled (desirable) fashion.

BTW, why are simple posts, like my first one, constantly met with snarky responses from you, like all of yours?

Edited to add: apologies to Shooting Sight. I realize the intention of the thread is to reduce the violence of suppressed recoil and appreciate it. Sorry for the derail.
« Last Edit: August 31, 2017, 06:40:14 AM by Hkbeltfed » Logged
RabbitSlayer
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« Reply #29 on: August 31, 2017, 03:30:43 PM »

I don't need to read volumes of books to comprehend a simple concept.  Instead of telling us to go read a book; why don't you simply explain the solution we are looking for?
If you have a better solution than adjusting recoil spring weight for our Tavors being overgassed when using suppressors, I am sure we would all love to hear it.  BTW, for those of us shooting 556 Tavors, an adjustable gas block is not an option.

Also, I have a hard time seeing how the pistol reference is irrelevant.  Both blowback operated and gas operated firearms actions timing work in direct correlation with the recoil spring weight.  Many people refer to blowback operation as a simplified form of gas operation.
The #1 suggestion people get in regards to having an overgassed firearm is to use a heavier recoil spring/buffer, so I think the most logical route for us here is to at least try a heavier recoil spring.

But by all means, if you have a better idea please ''enlighten'' us.

I get it, you're a know-it-all and you don't read. That's why this is a waste of time. I'm not suggesting you read volumes. I'm suggesting you refer to facts from an engineer who wrote volumes on firearms mechanisms including all of the science, formulas, and math behind it.

First you're comparing the Tavor to a handgun with a browning action where the barrel recoils with the slide and now you're referring to it as blowback which is incorrect and another type of action. Again, if you don't know the difference between locked breech, a Browning type, and blowback, look it up. That said, if you think blowback is relevant... http://www.orions-hammer.com/blowback/

An excerpt re: blowback: "NOTE: There is one point which requires special clarification at this time.  In many descriptions of blowback actions, it is strongly implied that the driving spring contributes a substantial portion of the resistance which limits acceleration imparted to the bolt by the powder gases.  Actually, this is not so.  Although it is true that the driving spring absorbs the kinetic energy of the recoiling bolt and thus limits the total distance it moves, the resistance of the spring does not have any real effect in the early phase of the cycle of operation.  The bolt acceleration occurs mainly while the powder gas pressures are high and are exerting a force of many thousands of pounds on the bolt.  The driving spring, in order to permit the bolt to open enough to allow feeding, must offer a relatively low resistance.  Although this resistance is sufficient to absorb the bolt energy over the comparatively great distance through which the bolt moves in recoil, it is not great enough to offer significant opposition to the powder gas pressure until the chamber pressure has dropped to a relatively low level well after the projectile has left the muzzle."

The solution you're looking for is an adjustable gas mechanism. The fact that you feel it's not an option is more ignorance in line with you narrow minded, know-it-all thinking in your posts above. Beyond that, its to vent excess gas in a controlled (desirable) fashion.

BTW, why are simple posts, like my first one, constantly met with snarky responses from you, like all of yours?

Edited to add: apologies to Shooting Sight. I realize the intention of the thread is to reduce the violence of suppressed recoil and appreciate it. Sorry for the derail.

God I hate pseudo intellectuals.


Edit: Thread derailed, want this to get back on topic.
« Last Edit: September 08, 2017, 10:03:51 PM by RabbitSlayer » Logged

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RabbitSlayer
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« Reply #30 on: August 31, 2017, 06:33:06 PM »


The solution you're looking for is an adjustable gas mechanism. The fact that you feel it's not an option is more ignorance in line with you narrow minded, know-it-all thinking in your posts above. Beyond that, its to vent excess gas in a controlled (desirable) fashion.

BTW, why are simple posts, like my first one, constantly met with snarky responses from you, like all of yours?

This thread is about a heavier recoil spring, not an adjustable gas block.  Do you know where to buy an adjustable gas block for the 556 Tavor?  Are you going to fund the research and development to build an adjustable gas block for the 556 Tavor?
The answer to both of those questions is no, so f-ck off.
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Hkbeltfed
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« Reply #31 on: August 31, 2017, 08:11:41 PM »

If I have ruined this thread, then I'm sorry. That said, you have gone off the deep end. I guess your questions will remain unanswered. You can take solace in the following...

I think you are 100% correct.  If reduction of gas is the only goal here, the spring is not the answer.  A reduced flow valve would be the way to do that.
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45r
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« Reply #32 on: September 02, 2017, 11:55:07 PM »

Tuning the gas will give better results than anything done with springs.
Hope you can make it work but nobody has yet.
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ShootingSight
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« Reply #33 on: September 08, 2017, 08:35:34 AM »

So I put this at 3 people interested, and 2 possibles...

This spring will slow the action and the thump of the BCG hitting the hard stop at the end of the travel.  However the piston vents the gas in the first 10% of its stroke, so it will do little to reduce the amount of gas that is vented into the gun/face.

So is it still worth it?  Seems like people are shooting without it, and report few problems with the recoil - most issues are with the gas.
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Art Neergaard
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AZ-Chris
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« Reply #34 on: September 08, 2017, 10:06:09 AM »

I'm still interested.  Slowing the bolt down will fix the minor reliability issues I've experienced (occasional failure to eject and the brass gets beat up pretty bad).  Gas in the face, while somewhat annoying, isn't a reliability problem.
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SteveG75
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« Reply #35 on: September 08, 2017, 09:50:09 PM »

I am interested as well.
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ShootingSight
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« Reply #36 on: September 15, 2017, 01:06:54 AM »

OK, I pulled the trigger and placed an order.  We'll know in several weeks.

If you want in for $50 for 2 springs, email me at art@shootingsight.com.  There are no guarantees.  I guessed at the 25% more power.  Good thing is with a Dremel and a cutoff wheel, you can remove loops one at a time, and since you are getting 2 springs, you can't go too far.

I ran the math, and while we are starting at a spring that absorbs 25% more energy through the stroke, you reduce that almost exactly 1% per loop you cut off, so you cut off 3 loops, you now only absorb 22% more energy through the stroke.

Once these work, I'll put them up for $35 each, so I'll let you struggle with the decision if you want in early at a reduced price per spring, but a slightly higher overall.

There has been confirmation in this thread that these will work for either the Tavor or the X-95.  Of course you can bet we will repeat this product for the .308 Tavor when it comes out.
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Art Neergaard
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AZ-Chris
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« Reply #37 on: September 15, 2017, 12:19:40 PM »

OK, I pulled the trigger and placed an order.  We'll know in several weeks.

If you want in for $50 for 2 springs, email me at art@shootingsight.com.  There are no guarantees.  I guessed at the 25% more power.  Good thing is with a Dremel and a cutoff wheel, you can remove loops one at a time, and since you are getting 2 springs, you can't go too far.

I ran the math, and while we are starting at a spring that absorbs 25% more energy through the stroke, you reduce that almost exactly 1% per loop you cut off, so you cut off 3 loops, you now only absorb 22% more energy through the stroke.

Once these work, I'll put them up for $35 each, so I'll let you struggle with the decision if you want in early at a reduced price per spring, but a slightly higher overall.

There has been confirmation in this thread that these will work for either the Tavor or the X-95.  Of course you can bet we will repeat this product for the .308 Tavor when it comes out.

email sent.  I'm in for $50 and 2 springs.
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RabbitSlayer
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« Reply #38 on: September 16, 2017, 01:36:01 AM »

In
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« Reply #39 on: September 16, 2017, 07:56:49 PM »

OK, I put up a product on my web site.  I made it 3 springs for $50 to sweeten it.  If we find a benefit we like, they will be $30 each after we conclude R&D, so getting in early is about half the cost per spring.
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Art Neergaard
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