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Author Topic: Stronger recoil spring for suppressed Tavor  (Read 4786 times)
pilot4prophet
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« Reply #40 on: September 17, 2017, 07:10:42 AM »

Shooting Sight,  Unable to add the item to the cart. Says out of stock.
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chowser51
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« Reply #41 on: September 17, 2017, 07:26:36 AM »

ditto. can't add to cart.
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« Reply #42 on: September 17, 2017, 09:54:39 AM »

OK, fixed it.  I put it as out of stock, but to allow backorders.  Frankly, I'm not impressed with the shopping cart software GoDaddy provides.

So now it is in stock.  Thanks for letting me know.
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Art Neergaard
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AZ-Chris
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« Reply #43 on: September 17, 2017, 04:37:26 PM »

I just placed my order.  Thanks again Art for taking on this project!
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ShootingSight
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« Reply #44 on: September 28, 2017, 03:22:33 PM »

Wow, that was fast!  New springs are in!

A few people got in on the 3 for $50 deal up front, so their springs are out in the mail.  I'll leave the deal up for the next few days in case someone wants in soon.  They will go up to $30 each this weekend.

I just opened the box, have not even installed one in my Tavor yet, let alone shot it, so I have no results to report, but was just excited and wanted to let people know.

Art
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Art Neergaard
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« Reply #45 on: September 28, 2017, 09:19:52 PM »

Someone just asked what harm could come from this, especially firing unsuppressed, so I figured: let's brainstorm everything we think could go wrong.

Spring has 25% more energy in it, so when the bolt closes, it will close faster.  I can't imagine that would hurt the rifle.  The two things I can think of are:

1.  If you have a misfeed, it will really jam the round in there. 
2.  The other thing is that the firing pin spring has to hold the pin back against a harder closing, so there could be a risk of a slam fire.  I'd test these with only 1 or 2 in the mag the first time.

Also, the obvious failure is the inability to cycle the gun unsuppressed.

The gun will cycle slower, but that should be a plus for trigger reliability.

Anything else?

Art
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Art Neergaard
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« Reply #46 on: September 28, 2017, 10:29:27 PM »

I believe cycling your action ( pulling your charging handle back and letting it slam forward ) with no ammo in the gun is probably harsher than the gun cycling with the 25% spring with it stripping ammo out of the mag.
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« Reply #47 on: September 29, 2017, 01:31:40 PM »

Wonder how much energy it takes to strip a round.

I have never heard of issues from dry cycling with a normal spring.  So is cycling with a +25% spring and ammo better or worse than a normal spring without ammo?

On a related - I just bought a high speed camera, so when I test this spring, I'll film it, and we can see how the cycling is different in speed and in stroke length.  Ohhhhh! That will be cool.
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Art Neergaard
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« Reply #48 on: September 30, 2017, 01:32:07 AM »

Dry cycling should be no problem at all.

Can't answer the other questions, but I highly doubt the 25% spring would cause any damage.  The Tavor is build out of the same type of materials that 308 semi autos are built out of, those have harsher springs and whatnot so I doubt there will be issues.

Bolt guns are made out of softer metals and shoot calibers like 300 mag...

I doubt the spring would hurt the gun in any way.  But, it could cause cycling issues till we figure out the propper +% ratio.
In the end it should all be worth it.


That is awesome you have a high speed camera, I seriously cannot wait to see that footage !
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« Reply #49 on: September 30, 2017, 08:55:46 AM »

Next question is where the sweet spot is.  I see two possibilities.

If you get the spring such that it just barely cycles with a suppressor, that is ideal for the suppressed mode, but then it will not cycle unsuppressed.

Question is if the OEM spring still lets the BCG smack back full-stroke with energy to spare when firing unsuppressed, you could boost the spring power till unsuppressed just barely cycles (with a margin to assure reliability).  That would mean suppressed is not as tame as it could be, but at least you found a common window, so the spring cycles in both modes.
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Art Neergaard
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pilot4prophet
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« Reply #50 on: October 03, 2017, 06:34:32 AM »

Got my springs today, Thanks Art!
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AZ-Chris
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« Reply #51 on: October 03, 2017, 07:35:57 PM »

Mine arrived too.  Thanks Art!
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« Reply #52 on: October 03, 2017, 08:31:18 PM »

Don't forget to post results.  I don't know when I'll get out to test, but I only have a 30 cal can, which likely will not give the back pressure that a true 223 can will.
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Art Neergaard
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AZ-Chris
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« Reply #53 on: October 03, 2017, 10:32:50 PM »

I just installed the new stiffer spring.  I hope to get out to the range tomorrow with my GemTech Trek 5.56 can.
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AZ-Chris
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« Reply #54 on: October 05, 2017, 01:54:22 PM »

I just got back from the range, having only run 3, 30-round magazines of XM193.  The first 30 rounds were fired un-supressed with ZERO malfunctions.  I could not really tell the difference in the bolt cyclic rate and the brass ejected in the 3 o'clock direction.  The recoil impulse seemed a bit stronger than with the stock spring.

The next two magazines were spent using my GemTech Trek 5.56, thread-on suppressor.  Again, there were ZERO malfunctions.  The bolt cyclic rate was clearly slower than when using the stock spring, but it's still faster than I would prefer.  The brass was ejecting between 1 and 2 o'clock (with most cases going forward of the firing line and therefore irretrievable).  Of the cases I was able to recover, most had a visible dent in case about 2/3 the way up from the base.

I measured the pull weight of the charging handle with the new, stiffer spring (using a portable luggage scale) and found it to be between 25 & 30 lbs to lock the bolt back.  I didn't think to measure this with the stock spring.

So far, I think the new, stronger spring is a definite improvement over the stock spring, though I think an even stronger spring may be better.
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« Reply #55 on: October 05, 2017, 04:38:01 PM »

I just got back from the range, having only run 3, 30-round magazines of XM193.  The first 30 rounds were fired un-supressed with ZERO malfunctions.  I could not really tell the difference in the bolt cyclic rate and the brass ejected in the 3 o'clock direction.  The recoil impulse seemed a bit stronger than with the stock spring.

The next two magazines were spent using my GemTech Trek 5.56, thread-on suppressor.  Again, there were ZERO malfunctions.  The bolt cyclic rate was clearly slower than when using the stock spring, but it's still faster than I would prefer.  The brass was ejecting between 1 and 2 o'clock (with most cases going forward of the firing line and therefore irretrievable).  Of the cases I was able to recover, most had a visible dent in case about 2/3 the way up from the base.

I measured the pull weight of the charging handle with the new, stiffer spring (using a portable luggage scale) and found it to be between 25 & 30 lbs to lock the bolt back.  I didn't think to measure this with the stock spring.

So far, I think the new, stronger spring is a definite improvement over the stock spring, though I think an even stronger spring may be better.


Thank you for the report.  I don't think the ejection pattern is as indictive to proper gas pressure as with a DI AR, I think the piston system of the Tavor probably has a different ideal ejection pattern.  However judging by your description, it does sound like the can is causing some over pressure for you, or at least more noticable pressure increase.
FWIW my stock x95 gives brass the same dents.
Just curious did you notice any less blowback with the stiffer spring by chance?  My stock gun can get pretty gassy once I start rapid firing, most of the gas leaks out of the rear of the optic rail/gas tube.
Did the new spring fit pretty easy?
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« Reply #56 on: October 05, 2017, 06:12:34 PM »

Wow, Chris, thanks for the excellent report.

I find it interesting that 25% more energy still cycles unsuppressed fine.  I wonder how much higher we can go, or if we should just run with it and say 25% extra is an improvement.

I am delighted that there is a window which improves suppressed fire, and still allows unsuppressed fire.  Makes me think the design goal ought to be to find the strongest spring that will still cycle unsuppressed.
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Art Neergaard
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AZ-Chris
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« Reply #57 on: October 05, 2017, 06:16:39 PM »

Spring replacement is quite easy and took all of 10-minutes, though you do have to push harder to compress the spring getting the retaining collar on.

The brass ejection pattern is different for me when shooting suppressed.  I've never had the brass shoot forward that much before . . . in fact I've had multiple complaints from people to my right that spent brass nails them pretty good (at my outdoor range).  With the new spring, the brass is traveling a good 6-10 feet forward.  The gun is just as gassy with the new spring, especially when shooting rapidly, so I say there's no improvement on that.  (I also get most of the gas coming from the rear of the rail).

Also, unsupressed, the brass cases do not get dented.

« Last Edit: October 05, 2017, 06:27:42 PM by AZ-Chris » Logged
AZ-Chris
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« Reply #58 on: October 05, 2017, 06:25:23 PM »

Wow, Chris, thanks for the excellent report.

I find it interesting that 25% more energy still cycles unsuppressed fine.  I wonder how much higher we can go, or if we should just run with it and say 25% extra is an improvement.

I am delighted that there is a window which improves suppressed fire, and still allows unsuppressed fire.  Makes me think the design goal ought to be to find the strongest spring that will still cycle unsuppressed.

Hi Art, the new spring is a definite improvement as far as I can tell, but I do want to shoot it more as well as try out my Rugged Razor, 30-cal can.

Given your earlier comments about the spring, I was delighted when I experienced no trouble shooting unsupressed.  The recoil impulse did feel a bit sharper, and I wasn't paying attention to muzzle rise. 

Overall, I think a stronger spring would be even better, but I'm happy with the new spring.  Thanks for making that happen!
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AZ-Chris
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« Reply #59 on: October 06, 2017, 06:54:55 PM »

Just got home from my 2nd range session, this time using my Rugged Razor, 30-cal suppressor and 3, 30-round magazines of XM193.

The first 30 rounds were fired unsuppressed and again, I had zero malfunctions . . . flawless operation.  Shells ejected at the usual 3 o'clock position and I saw no damage to the brass cases.  Muzzle rise might have been a little more pronounced, but not by much and since I was going to use the Rugged Razor, I needed to use the Rugged flash hider muzzle device in lieu of usual compensator.

I then proceeded to fire another 2 magazines suppressed.  The shells ejected between 2 and 3 o'clock and not quite as forcefully as when I used my GemTech Trek.  The cases were still a bit dented in the same place as yesterday (about 2/3 the way up from the base).

I can say, without a doubt, that the new, stronger recoil spring is an improvement over stock when shooting suppressed (bolt speeds are noticeably slower and less violent) and makes little to no difference when shooting unsuppressed.  I did NOT notice any significant impact on gassyness . . . it is what it is.

I'd be interested in trying a still stronger recoil spring if there is further interest, but I'm very glad I have this new spring because it does adequately address my biggest concern about shooting the Tavor suppressed.

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