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Buffer spring effect on accuracy???

#51
Re: Buffer spring affect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BattleAxe</div><div class="ubbcode-body">If I wore a spring out and needed a new one I may try one if similarly priced to a factory spring but I wouldn't pay much more. </div></div>

The difference in price is less than a box of bullets. Is that too big of a risk to see if there is an accuracy improvement?

Hell, I have blown more than a hundred bucks work of ammo dialing in a rifle. Paying $20 more for a spring isn't even a drop in the bucket on some of these weapon systems.
 
#52
Re: Buffer spring affect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: LoneWolfUSMC</div><div class="ubbcode-body">The difference in price is less than a box of bullets. Is that too big of a risk to see if there is an accuracy improvement?

Hell, I have blown more than a hundred bucks work of ammo dialing in a rifle. Paying $20 more for a spring isn't even a drop in the bucket on some of these weapon systems. </div></div>

I see your point but to my point...I have a AR10 that prints 7 inch groups at 850 yards in what are typically poor conditions. Lets say I go out and buy the lastest cuzivit (cuzivit wasn't there your trigger would fall off). After installation I go out and knock out a string of half-minute groups at that distance and I notice I'm generally shooting better following this installation. One or more of several things are true...

1. I spent $30
2. This thingy really works
3. This thingy doesn't work at all
3. My eyesight was really good today
4. My trigger control was really good today
5. I've overcome a plateau
6. I've improved
7. I got a really good batch of ammo
8. Atmospherics improved
9. I slept better the night before
10. I got laid the night before
11. The fire ants weren't attacking me today
12. Dang...that was some really good weed

etc. etc.

In the end there's no way you can accurately proclaim that it works when all you have is a theory and someone's good day at the range to go by. I'd try one if my spring goes tits-up but my rifle ain't broken and I'm not going to leap just because its there. I made that mistake once and I won't repeat it.
 
#53
Re: Buffer spring affect on accuracy???

The whole buffer spring thing has me quite interested. First, this is pretty cheap for a test.

Is there at least universal recognition that a "bad" spring would cause issues? I think that there is, and if there is disagreement with that, please, someone, state that.

I come from a motorcycle racing background. The suspension is the direct contact to the ground in addition to being what can help one utilize whatever skills one has to their fullest that day. One can use spring rate and even spring design to achieve a better handling bike, period. Yes, there is usually a recognized spring rate that is deemed to be correct. And springs are given a numerical rate and some spring manufacturers go so far as then actually bench testing the exact rate and recording that on the spring. Example, I need a 450# spring for my bike weight, my weight, and the application. I order a 450# spring, and the spring comes with a scribe mark on it stating it is 445#, which is reasonable. From there, I can tune the bike. Maybe I like a stiffer spring or maybe I'm going to race in the rain. I can make changes.

Anyway, I've never noticed any kind of rating or much for part numbers on the buffer springs, not that I've looked much. Does anyone rate them? I know what an under or over sprung bike is like, so I guess I can work out issues in my head on how spring rates could affect the timing and operation of the AR system.

$30 is still cheaper than a spring or a set of springs for a bike.
 
#54
Re: Buffer spring affect on accuracy???

Why not try the Tubbs spring and the Tubbs carrier weight system. They work together, As do his springs for trigger and extractor. I'll go pop the corn and wait for input/replys. By the way anybody ever hear from the guy with the shitty hat????
 
#55
Re: Buffer spring affect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Scot</div><div class="ubbcode-body">Why not try the Tubbs spring and the Tubbs carrier weight system. They work together, As do his springs for trigger and extractor.</div></div>
Sure! But I think that's for a 556/223 set up. I'm 308.
 
#56
Re: Buffer spring affect on accuracy???

Considering how competive the AR10 market has become, and how accurate these platforms have become I find it interesting that manufacturers haven't latched onto this and started using better springs. After all these springs aren't new and builders would kill to achieve an edge.
 
#57
Re: Buffer spring affect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BattleAxe</div><div class="ubbcode-body">Considering how competive the AR10 market has become, and how accurate these platforms have become I find it interesting that manufacturers haven't latched onto this and started using better springs. After all these springs aren't new and builders would kill to achieve an edge. </div></div>
Agreed.

Thinking out loud, if one were truly "doing it right", I would think that one could customize spring rates to each load. I would bet that a 308 with a 175g might produce a different reaction to the platform than a 6.5 Creedmoor with a 140g...or insert your variables here.

I would think as a production company, one might look for the "compromise". But, again, a "custom" $30 spring is pretty cheap for a test.
 
#58
Re: Buffer spring affect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Super Dave</div><div class="ubbcode-body">I would bet that a 308 with a 175g might produce a different reaction to the platform than a 6.5 Creedmoor with a 140g...or insert your variables here.</div></div> That's almost a no-brainer which is why I'm a little leery about this. That and the fact that even lower end .308 autos are pretty good shooters with normal springs and in the right hands.
 
#59
Re: Buffer spring affect on accuracy???

This tread made me pull my head out. The ar15 Tubb spring is the same one for rifle and carbine ( really long compared to stock carbine spring ), so measured some brand new 69 gr Lapua rounds for OA length, loaded in magazine and chambered some rounds with Tubb spring and with stock Armalite spring. The test was done with AR15 carbine and will repeat in future with rifle and AR10 rifle and carbine.
After cambering with Tubb spring OA length increased an average of .005.
After cambering with stock spring OA length increased an average of .001.
A stronger spring acts like an inertia puller and would be even more effective with a heaver bullet.
Stock spring is now permanently installed in carbine, will check others in future
 
#61
Re: Buffer spring affect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Super Dave</div><div class="ubbcode-body">I come from a motorcycle racing background.</div></div>

Remember that buffer springs in a AR serve a much different purpose than suspension in a bike.

If you really want to tinker, I am sure you could find some springs of an appropriate diameter with different rates. They are just springs after all. There isn't any magic to them.
 
#62
Re: Buffer spring affect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: LoneWolfUSMC</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Super Dave</div><div class="ubbcode-body">I come from a motorcycle racing background.</div></div>

Remember that buffer springs in a AR serve a much different purpose than suspension in a bike.

If you really want to tinker, I am sure you could find some springs of an appropriate diameter with different rates. They are just springs after all. There isn't any magic to them. </div></div>
The carrier has a weight, a distance of travel that it is limited to, there is a function that occurs during that travel, and there is an input placed into it that is to be controlled.

No, it isn't going over bumps, but it is an incredibly similar function that certainly relies upon its operation as the result of spring rate and variations of manipulation that come from compressing a spring.
 
#63
Re: Buffer spring affect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ElCoyote</div><div class="ubbcode-body">
A stronger spring acts like an inertia puller and would be even more effective with a heaver bullet.
Stock spring is now permanently installed in carbine, will check others in future </div></div>
I listened to the explanation of the spring this morning again. My understanding is that the spring has higher initial spring rate. However, as it is compressed, the rate does not increase at the same rate as a regular wire spring. To me, this appears obvious when looking at the two compressed springs, his and an OEM style spring. As an OEM style spring starts to compress, it eventually starts to have coils that begin to touch each other, and that results in a dramatic increase in spring rate...not linear. Once the assembly stops moving, it now is going to change direction based upon that rate that it stopped at, which is much higher than the Tubb spring that should be able to continue its compression of the spring in a linear fashion, and it's rebound should be less severe.

Just thinking out loud again.
 
#64
Re: Buffer spring affect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Super Dave</div><div class="ubbcode-body">
I come from a motorcycle racing background. </div></div>

Maybe if Ohlins made a spring we'd be in business...
laugh.gif
of course it would have to have adjustable pre-load, with some rebound and compression settings adjustable via set screws at the end of the butt stock....

Which would mean that it'd need to be hydraulic, and then we could play with some fork oil weights to get it just right. Can you say $1,285 for a buffer tube assembly? But in the name of accuracy!

2 wheels and a puck...
laugh.gif
 
#65
Re: Buffer spring affect on accuracy???

I hear ya...

Ohlins came make what they want, but I think they outsource a lot of springs.

I'd be buying a Penske.
grin.gif
 
#67
Re: Buffer spring affect on accuracy???

I just tried a Tubb spring in my AR15/ Magpul UBR standard car buffer/ mid-gas 16" Kreiger, and I must say I like very much how the action feels now.

Seems to be a little more consistent on paper and the bolt lockup is more positive...not necessarily harder, but positive.

I explained it to a friend as "Its like closing the door on a KIA vs a BMW, the BMW just sounds better"

I don't know how else to explain it but I will be using one from now on. The rifle just feels better.
 
#68
Re: Buffer spring affect on accuracy???

I personally like the Tubb springs. Increase accuracy? Who knows. What I do know and understand, it will last longer, and it is more efficient in its operating area, By that I mean that its at a constant rate throughout its compression range. I like that. I can't say it has ever increased accuracy in any rifle I have it in, (5) but it will be one of the last parts to wear out and they have all functioned more reliably with that spring installed. Its not that expensive really. I also like the extractor springs. To me using a donut or plastic insert is more of a band-aid fix than a true solution. Its like using your bumpstops on your suspension to increase spring rate at full load, than using a properly set up suspension to begin with. Using stock parts and 18 years of M16's I have seen a few failures of the buffer spring. Just being worn out so its too short and lost its ability to work well, to a few that were broken. Have seen alot of extractor failures that were spring related as well. Also I have seen some XM-16's ( not even an A1) with original parts in it still run fine. Just luck of the draw with mass produced parts sometimes. Everything and anything mechanical can, will or has failed at some point. The CS springs just minimize this and are a better technology than was available or used at the time of design. Its good to have a little extra efficiency where you can get it. End of the day, it certainly won't hurt it.
 
#69
Re: Buffer spring affect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: pupdawg</div><div class="ubbcode-body">I just tried a Tubb spring in my AR15/ Magpul UBR standard car buffer/ mid-gas 16" Kreiger, and I must say I like very much how the action feels now.

Seems to be a little more consistent on paper and the bolt lockup is more positive...not necessarily harder, but positive.

I explained it to a friend as "Its like closing the door on a KIA vs a BMW, the BMW just sounds better"

I don't know how else to explain it but I will be using one from now on. The rifle just feels better. </div></div>

Thats pretty much what the right spring does for an AR. I explained the technical effects of consistent carrier velocity, repeatable lockup and maintianing the lockup longers effects on both practical and mechanical accuracy earlier in this thread.

You summed it up quite nicely
 
#70
Re: Buffer spring affect on accuracy???

I built my first AR with a used stock, tube and spring. Since I reload, the first thing I notice was how the fired casings came out sooted and black. I swapped the factory spring for a Tubb unit and cases were 75% cleaner. Never did check to see what if any effect the premature bolt release had on accuracy, but seams reasonable to conclude that pressure lost through chamber could hamper accuracy and consistency.
 
#71
Re: Buffer spring affect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Awesymoto</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Super Dave</div><div class="ubbcode-body">
I come from a motorcycle racing background. </div></div>

Maybe if Ohlins made a spring we'd be in business...
laugh.gif
of course it would have to have adjustable pre-load, with some rebound and compression settings adjustable via set screws at the end of the butt stock....

Which would mean that it'd need to be hydraulic, and then we could play with some fork oil weights to get it just right. Can you say $1,285 for a buffer tube assembly? But in the name of accuracy!

2 wheels and a puck...
laugh.gif
</div></div>


No, use this
laugh.gif


fox-racing-show-original-airshox-air-shock.jpg
 
#73
Re: Buffer spring affect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Grand</div><div class="ubbcode-body">I built my first AR with a used stock, tube and spring. Since I reload, the first thing I notice was how the fired casings came out sooted and black. I swapped the factory spring for a Tubb unit and cases were 75% cleaner. Never did check to see what if any effect the premature bolt release had on accuracy, but seams reasonable to conclude that pressure lost through chamber could hamper accuracy and consistency. </div></div>

Premature bolt unlocking is why bolts were failing around 5k to 6k rounds and why Crane NSWC replaced their bolts at 4,500 rounds and FBI HRT at only 1k rounds. With a 7" gas tube gun you get twice the peak pressure as the 12" rifle length guns. The longer the barrel on a 7" gas system gun, the worse the problem. Once the stock (low bid) spring takes its full initial set at about 600 to 800 rounds, the spring was not maintaining sufficient force against the bolt carrier to keep the bolt in battery long enough, so you got premature opening and blow back through the chamber, which is partly responsible for the bad rap (guns run dirty) against the M4 and direct gas impingement.

Of course the solution is proper timing achieved through proper gas port placement relative to barrel length and then using the proper spring, but I diverge here...

The main points here, relative to accuracy, is the variations in velocity this condition can induce. Every serious competition shooter knows one of the keys to maximum accuracy is ammunition with a low standard deviation (SD) and this condition in AR's screws SD all to hell. The other issue is the harmonics that can be induced when you get significant carrier movement while the bullet travels down the barrel. Not to mention the effect on consistent and repeatable return to battery I covered before.

Why chrome silicon springs provide a degree of improvement is they take less of set and typically lose a smaller percentage of their original strength. CS springs also provide a more uniform compression rate across the full compression cycle, which means it provides a greater percentage of its full spring rate as full extension vs. standard springs. This allows the bolt to stay closed longer which helps bullets get to full velocity and the bullet has typically left the barrel before significant bolt or carrier movement have occurred.

So, in my humble opinion your conclusions are more than reasonable they are supported by solid data.

Regards,

-E
 
#74
Re: Buffer spring affect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: fngmike</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Awesymoto</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Super Dave</div><div class="ubbcode-body">
I come from a motorcycle racing background. </div></div>

Maybe if Ohlins made a spring we'd be in business...
laugh.gif
of course it would have to have adjustable pre-load, with some rebound and compression settings adjustable via set screws at the end of the butt stock....

Which would mean that it'd need to be hydraulic, and then we could play with some fork oil weights to get it just right. Can you say $1,285 for a buffer tube assembly? But in the name of accuracy!


2 wheels and a puck...
laugh.gif
</div></div>


No, use this
laugh.gif


I can see it now, an adjustable unit with remote resivoir for those full auto guys. How cool would that be...
cool.gif



fox-racing-show-original-airshox-air-shock.jpg
</div></div>
 
#75
Re: Buffer spring affect on accuracy???

Lots of ifs....

If anything is going to aid bolt lock-up in an AR-10 it will be add-on weight in the buffer or a kit for the boltcarrier.

If you think a heavier spring is what keeps your bolt engagement constant, or shows that it does, your bolt lugs are worn or you have a sloppy barrel extension...

If the spring rate is significantly different you're gonna short-stroke or over-ride the BCG unless buffer weight or carrier weight is also adjusted. The gas system is a balancing act at all times. Might go to a variable port gas block as one mode of control.

Another variable is lubrication. Got your buffer/recoil spring lubed up with wheelbearing grease? Sewing machine oil? Synth 20/50? Are you lubing your boltcarrier and upper receiver rails sufficiently?

Are you sure your buffer & spring are in specs for length and weight before you begin jacking with the equation?

Hows that ammunition? Match quality or ball with minimal pressure variations? Isolate the variables and look at the whole system from gas port in barrel to BC Key and then into the recoil/feeding system. If M4 cut receiver, do you have M4 cuts on your barrel extension? If carbine length gas system, are you sure you have a proper AR-10 carbine gas tube? The lengths do differ from mid-length AR-15...
 
#76
Re: Buffer spring affect on accuracy???

I found it interesting that Tubbs does not differentiate in spring length between carbine and midlength Ar 15 systems. I installed Tubbs springs in both a Carbine(LMT) and Midlength(Noveske) and had short stroking problems. And Yes I used different buffer weights to try and clear it up, to no avail. After contacting Tubbs and inquiring if they had encountered this problem, they indicated that yes they had. All I had to do was to cut the spring by 1/2 to 3/4 of a coil and it would be fine. Needless to say I wasnt pleased with this remedy(especially for what these things cost) and promptly switched back to Stock springs. No problems since. Perhaps I should not try and remedy that which is not broken?
 
#77
Re: Buffer spring affect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: RedCreek</div><div class="ubbcode-body">. So, assuming an AR was properly sprung to begin with, when that spring looses 10% of its efficiency and that loss yielded a 10% increase in carrier velocity this would in turn result in a 40% increase in energy of the carrier.
</div></div><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: RedCreek</div><div class="ubbcode-body">Its 40%

If you increase the velocity of an object you quadruple the engery and if you double the weight you only double the energy.

Speed x weight / 64.32 = energy

I would share with you the test results from a DoD project we did, but then I would have to kill you
shocked.gif


Show me your math...

-E </div></div>
First a list of variables used:
(F_sp = spring force, k = spring constant, s = spring displacement from equilibrium, a = acceleration, m = mass, v(s) = velocity as a function of position, v_0 = initial carrier velocity, v(s)_2 = carrier velocity when weak spring is used)

As for the part about a 10% increase in velocity:

F_sp = -k s

Once the rifle has fired and the carrier is moving rearward with velocity v_0, the acceleration of the carrier (neglecting friction) is:

a = F_sp/m = (-k s)/m

Integrate with respect to the position from spring equilibrium:

v(s)^2 = -k/m/2*s^2 + v_0^2

With a 10% loss in spring constant this becomes:

v(s)_2^2 = -.9k/m/2*s^2 + v_0^2

Divide out the 9/10, subtract the newly created remainder of v_0, substitute the identity for v(s)^2 into the v(s)_2^2 equation, move the remainder back, multiply back in the 9/10 and take the square root and you are left with:

--------------------------------------
v(s)_2 = sqrt(9/10*(v(s)^2+1/9*v_0^2))
--------------------------------------

This equation shows that the velocity of the carrier being controlled by the 10% weaker spring is dependent on the initial velocity of the carrier, and does not simply equal 10% more velocity than it would have had with a proper spring. This relationship was verified by computer model.


As for the second part of your post, kinetic energy is half the mass times velocity squared, so the original kinetic energy is m/2*v^2 (your equation would be correct for ft,lb,s units if you had remembered to square your velocity term). The kinetic energy of the carrier with the weakened spring is m/2*9/10*(v(s)^2+1/9*v_0^2). Again there is a dependency on the initial velocity, so it cannot be solved without initial conditions.

However, if the carrier velocity just so happens to be 10% greater than normal, energy would <span style="font-style: italic">still</span> not increase by 40%. The energy at 110% of an arbitrary velocity, v, is m/2*(1.10v)^2. Square that 1.10, and you are left with 1.21. At this point you can simply bring that out of the equation and you are left with the original energy calculation multiplied by 1.21. That is to say, for a 10% increase in velocity, there is a 21% increase in energy for any combination of mass and velocity.

You are getting confused with the definition of energy. Doubling, not just increasing, the velocity will quadruple the energy.
 
#78
Re: Buffer spring affect on accuracy???

I always try to maintain that I before E except after C is not a constant, as evidenced by the word WEIRD, however I have found that in everyday use changing the Y to I and adding ES seems to be consistant,and I like the springs, as they have been consistant for me as well.
 
#79
Re: Buffer spring affect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 2ndPanzer</div><div class="ubbcode-body"> I always try to maintain that I before E except after C is not a constant, as evidenced by the word WEIRD, however I have found that in everyday use changing the Y to I and adding ES seems to be consistant,and I like the springs, as they have been consistant for me as well. </div></div>

+1.

I think.
 
#80
Re: Buffer spring affect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Kombar</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: RedCreek</div><div class="ubbcode-body">. So, assuming an AR was properly sprung to begin with, when that spring looses 10% of its efficiency and that loss yielded a 10% increase in carrier velocity this would in turn result in a 40% increase in energy of the carrier.
</div></div><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: RedCreek</div><div class="ubbcode-body">Its 40%

If you increase the velocity of an object you quadruple the engery and if you double the weight you only double the energy.

Speed x weight / 64.32 = energy

I would share with you the test results from a DoD project we did, but then I would have to kill you
shocked.gif


Show me your math...

-E </div></div>
First a list of variables used:
(F_sp = spring force, k = spring constant, s = spring displacement from equilibrium, a = acceleration, m = mass, v(s) = velocity as a function of position, v_0 = initial carrier velocity, v(s)_2 = carrier velocity when weak spring is used)

As for the part about a 10% increase in velocity:

F_sp = -k s

Once the rifle has fired and the carrier is moving rearward with velocity v_0, the acceleration of the carrier (neglecting friction) is:

a = F_sp/m = (-k s)/m

Integrate with respect to the position from spring equilibrium:

v(s) = -k/m/2*s^2 + v_0

With a 10% loss in spring constant this becomes:

v(s)_2 = -.9k/m/2*s^2 + v_0

Divide out the .9, subtract the newly created remainder of v_0, substitute the identity for v(s) into the v(s)_2 equation, move the remainder back, and finally divide everything by the 1.11 that was created when initially dividing by .9 and you are left with:

--------------------------------------
v(s)_2 = (v(s) + .11 v_0)/1.11
--------------------------------------

This equation shows that the velocity of the carrier being controlled by the 10% weaker spring is dependent on the initial velocity of the carrier, and does not simply equal 10% more velocity than it would have had with a proper spring. This relationship was verified by computer model.


As for the second part of your post, kinetic energy is half the mass times velocity squared, so the original kinetic energy is m/2*v^2 (your equation would be correct for ft,lb,s units if you had remembered to square your velocity term). The kinetic energy of the carrier with the weakened spring is m/2*((v(s) + .11*v_0)/1.11)^2. Again there is a dependency on the initial velocity, so it cannot be solved without initial conditions.

However, if the carrier velocity just so happens to be 10% greater than normal, energy would <span style="font-style: italic">still</span> not increase by 40%. The energy at 110% of an arbitrary velocity, v, is m/2*(1.10v)^2. Square that 1.10, and you are left with 1.21. At this point you can simply bring that out of the equation and you are left with the original energy calculation multiplied by 1.21. That is to say, for a 10% increase in velocity, there is a 21% increase in energy for any combination of mass and velocity.

You are getting confused with the definition of energy. Doubling, not just increasing, the velocity will quadruple the energy. </div></div>

So... you're saying I need the accuwedge?
wink.gif
jk
 
#81
Re: Buffer spring affect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Kombar</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: RedCreek</div><div class="ubbcode-body">. So, assuming an AR was properly sprung to begin with, when that spring looses 10% of its efficiency and that loss yielded a 10% increase in carrier velocity this would in turn result in a 40% increase in energy of the carrier.
</div></div><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: RedCreek</div><div class="ubbcode-body">Its 40%

If you increase the velocity of an object you quadruple the engery and if you double the weight you only double the energy.

Speed x weight / 64.32 = energy

I would share with you the test results from a DoD project we did, but then I would have to kill you
shocked.gif


Show me your math...

-E </div></div>
First a list of variables used:
(F_sp = spring force, k = spring constant, s = spring displacement from equilibrium, a = acceleration, m = mass, v(s) = velocity as a function of position, v_0 = initial carrier velocity, v(s)_2 = carrier velocity when weak spring is used)

As for the part about a 10% increase in velocity:

F_sp = -k s

Once the rifle has fired and the carrier is moving rearward with velocity v_0, the acceleration of the carrier (neglecting friction) is:

a = F_sp/m = (-k s)/m

Integrate with respect to the position from spring equilibrium:

v(s) = -k/m/2*s^2 + v_0

With a 10% loss in spring constant this becomes:

v(s)_2 = -.9k/m/2*s^2 + v_0

Divide out the .9, subtract the newly created remainder of v_0, substitute the identity for v(s) into the v(s)_2 equation, move the remainder back, and finally divide everything by the 1.11 that was created when initially dividing by .9 and you are left with:

--------------------------------------
v(s)_2 = (v(s) + .11 v_0)/1.11
--------------------------------------

This equation shows that the velocity of the carrier being controlled by the 10% weaker spring is dependent on the initial velocity of the carrier, and does not simply equal 10% more velocity than it would have had with a proper spring. This relationship was verified by computer model.


As for the second part of your post, kinetic energy is half the mass times velocity squared, so the original kinetic energy is m/2*v^2 (your equation would be correct for ft,lb,s units if you had remembered to square your velocity term). The kinetic energy of the carrier with the weakened spring is m/2*((v(s) + .11*v_0)/1.11)^2. Again there is a dependency on the initial velocity, so it cannot be solved without initial conditions.

However, if the carrier velocity just so happens to be 10% greater than normal, energy would <span style="font-style: italic">still</span> not increase by 40%. The energy at 110% of an arbitrary velocity, v, is m/2*(1.10v)^2. Square that 1.10, and you are left with 1.21. At this point you can simply bring that out of the equation and you are left with the original energy calculation multiplied by 1.21. That is to say, for a 10% increase in velocity, there is a 21% increase in energy for any combination of mass and velocity.

You are getting confused with the definition of energy. Doubling, not just increasing, the velocity will quadruple the energy. </div></div>

Wow! Impressive stuff...I'm too stupid to work out if it is real or fake science
laugh.gif


But if I ever needed a good reason to go and buy a bolt rifle....this is it!
 
#82
Re: Buffer spring affect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Kombar</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: RedCreek</div><div class="ubbcode-body">. So, assuming an AR was properly sprung to begin with, when that spring looses 10% of its efficiency and that loss yielded a 10% increase in carrier velocity this would in turn result in a 40% increase in energy of the carrier.
</div></div><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: RedCreek</div><div class="ubbcode-body">Its 40%

If you increase the velocity of an object you quadruple the engery and if you double the weight you only double the energy.

Speed x weight / 64.32 = energy

I would share with you the test results from a DoD project we did, but then I would have to kill you
shocked.gif


Show me your math...

-E </div></div>
First a list of variables used:
(F_sp = spring force, k = spring constant, s = spring displacement from equilibrium, a = acceleration, m = mass, v(s) = velocity as a function of position, v_0 = initial carrier velocity, v(s)_2 = carrier velocity when weak spring is used)

As for the part about a 10% increase in velocity:

F_sp = -k s

Once the rifle has fired and the carrier is moving rearward with velocity v_0, the acceleration of the carrier (neglecting friction) is:

a = F_sp/m = (-k s)/m

Integrate with respect to the position from spring equilibrium:

v(s) = -k/m/2*s^2 + v_0

With a 10% loss in spring constant this becomes:

v(s)_2 = -.9k/m/2*s^2 + v_0

Divide out the .9, subtract the newly created remainder of v_0, substitute the identity for v(s) into the v(s)_2 equation, move the remainder back, and finally divide everything by the 1.11 that was created when initially dividing by .9 and you are left with:

--------------------------------------
v(s)_2 = (v(s) + .11 v_0)/1.11
--------------------------------------

This equation shows that the velocity of the carrier being controlled by the 10% weaker spring is dependent on the initial velocity of the carrier, and does not simply equal 10% more velocity than it would have had with a proper spring. This relationship was verified by computer model.


As for the second part of your post, kinetic energy is half the mass times velocity squared, so the original kinetic energy is m/2*v^2 (your equation would be correct for ft,lb,s units if you had remembered to square your velocity term). The kinetic energy of the carrier with the weakened spring is m/2*((v(s) + .11*v_0)/1.11)^2. Again there is a dependency on the initial velocity, so it cannot be solved without initial conditions.

However, if the carrier velocity just so happens to be 10% greater than normal, energy would <span style="font-style: italic">still</span> not increase by 40%. The energy at 110% of an arbitrary velocity, v, is m/2*(1.10v)^2. Square that 1.10, and you are left with 1.21. At this point you can simply bring that out of the equation and you are left with the original energy calculation multiplied by 1.21. That is to say, for a 10% increase in velocity, there is a 21% increase in energy for any combination of mass and velocity.

You are getting confused with the definition of energy. Doubling, not just increasing, the velocity will quadruple the energy. </div></div>


That’s pretty impressive math.

I’m just using basic physics applied to actual weapons tests results.

So, basically, without factoring in the higher liner compression rate of standard vs. CS springs and the approx 20% greater load in battery, but just comparing a new standard spring with a worn spring where the worn spring allows the carrier velocity to increase by 10%, which is what the test have shown. Basic physics say that when velocity increases, the resultant energy imparted to the mass accelerated increases by a factor of four. Therefore, if a worn-out spring created an increase in the carrier velocity of 10% then, then the energy increases by 40%.
 
#83
Re: Buffer spring affect on accuracy???

Wow, you just don't know when to quit. There's no longer anything resembling basic physics in your argument. Since you don't seem willing to take my word for it, here's something you should be able to understand:

1. Go to JBM ballistics.
2. Click on "Ballistics" and then "Trajectory - Simplified".
3. Enter a velocity; lets say 1000 fps.
4. Note the energy.
5. Now enter a velocity that is 10% greater.
6. Note the new energy.
7. Divide this second value by the first.
8. Observe how wrong you are.
 
#84
Re: Buffer spring affect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Kombar</div><div class="ubbcode-body">Wow, you just don't know when to quit. There's no longer anything resembling basic physics in your argument. Since you don't seem willing to take my word for it, here's something you should be able to understand:

1. Go to JBM ballistics.
2. Click on "Ballistics" and then "Trajectory - Simplified".
3. Enter a velocity; lets say 1000 fps.
4. Note the energy.
5. Now enter a velocity that is 10% greater.
6. Note the new energy.
7. Divide this second value by the first.
8. Observe how wrong you are. </div></div>


First, I really don’t get what’s the deal with some of you guys out here on the forums.

I in no way challenged what you said. In fact, I said "that’s pretty impressive math"

I then simply explained how I came to my conclusions, plain and simple.

The following is from the website "The Physics Classroom"

<span style="text-decoration: underline"><span style="font-weight: bold">Kinetic Energy</span></span>

Kinetic energy is the energy of motion. An object that has motion - whether it is vertical or horizontal motion - has kinetic energy. There are many forms of kinetic energy - vibrational (the energy due to vibrational motion), rotational (the energy due to rotational motion), and translational (the energy due to motion from one location to another). To keep matters simple, we will focus upon translational kinetic energy. The amount of translational kinetic energy (from here on, the phrase kinetic energy will refer to translational kinetic energy) that an object has depends upon two variables: the mass (m) of the object and the speed (v) of the object. The following equation is used to represent the kinetic energy (KE) of an object.

u5l1c1.gif


where m = mass of object

v = speed of object

<span style="text-decoration: underline"><span style="font-weight: bold">This equation reveals that the kinetic energy of an object is directly proportional to the square of its speed. That means that for a twofold increase in speed, the kinetic energy will increase by a factor of four.</span></span> For a threefold increase in speed, the kinetic energy will increase by a factor of nine. And for a fourfold increase in speed, the kinetic energy will increase by a factor of sixteen. The kinetic energy is dependent upon the square of the speed. As it is often said, an equation is not merely a recipe for algebraic problem solving, but also a guide to thinking about the relationship between quantities.

<span style="font-style: italic">So, basically what they are saying here is that if you increase the velocity by 100% then you increase the energy by 400%, so then if the increase is only 10% then the energy increase would then be only 40%</span>

Kinetic energy is a scalar quantity; it does not have a direction. Unlike velocity, acceleration, force, and momentum, the kinetic energy of an object is completely described by magnitude alone. Like work and potential energy, the standard metric unit of measurement for kinetic energy is the Joule. As might be implied by the above equation, 1 Joule is equivalent to 1 kg*(m/s)^2.
 
#85
Re: Buffer spring affect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: RedCreek</div><div class="ubbcode-body">First, I really don’t get what’s the deal with some of you guys out here on the forums.

I in no way challenged what you said. In fact, I said "that’s pretty impressive math"</div></div>
Occasionally I feel compelled to act against misinformation; plus it's fun to try and figure out some of these problems. I did make a small mistake in the first part about the carrier velocity. The integration should have resulted in the velocity sqared as a function of position, which changes the relationship slightly between the the two velocities. Strangely enough, the old equation gave the same results within the range of velocities I was looking at, which is why it seemed to match the computer model I was using. The new equation: v(s)_2=sqrt(9/10*(v(s)^2+1/9*v_0^2)) matches the model much better.

As far as challenging what I said, you did that when you maintained your stance in spite of calculations which pretty clearly showed you were in error. Did you happen to notice how, in the very link you posted, the 300% increase in velocity equaled a 900% increase in energy, not 1200% as you would claim? Did you even bother to run some examples through a program that can calculate energy? If you do, you'll find that your assumption is false. An exponential relationship does not translate to a linear one. The end.
 
#87
Re: Buffer spring affect on accuracy???


Kombar/Redcreek, express your math in English. Whatcha sayn, chatty man? Give us your opinion and conclusions in a manner others who are not mathematicians can comprehend.
 
#89
Re: Buffer spring affect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Casey Simpson</div><div class="ubbcode-body">
Kombar/Redcreek, express your math in English. Whatcha sayn, chatty man? Give us your opinion and conclusions in a manner others who are not mathematicians can comprehend. </div></div>

Casey, its apparent they're saying we all need the Accuwedge in our AR's...
whistle.gif
wink.gif
 
#90
Re: Buffer spring effect on accuracy???

You have all gotten the best of my curiosity. Plus, I am always looking for more accuracy no matter where it comes from. I am going to invest $30 and do my own test. To be fair to the stock Armalite spring, I will use the Tubb's spring first for warm up. I will then reinstall the stock spring and determine the change in accuracy, if any. I will report back in a few weeks.
 
#91
Re: Buffer spring effect on accuracy???

I should have the Tubb spring in hand tomorrow. So, I may be able to conduct the test as early as this weekend if it is dry enough to get to where I shoot. Anyone have any input on how to make the test more scientific?
 
#92
Re: Buffer spring effect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: longeye51</div><div class="ubbcode-body">I should have the Tubb spring in hand tomorrow. So, I may be able to conduct the test as early as this weekend if it is dry enough to get to where I shoot. Anyone have any input on how to make the test more scientific? </div></div>

I dont know about scientific... but you should use the same ammo, preferably a factory match ammo as its more consistent than regular ball (ex: Black Hills Blue box, Federal Gold medal match, etc).

Do 5 or 6 5 shot groups with the spring and without the spring. Aside from that I have no idea what would be better.

The spring really does make the recoil impulse feel "smoother" and more positive.
 
#93
Re: Buffer spring effect on accuracy???

I will use Federal SMK 168 grain with both springs. Other than possibly me, all other shooting conditions should be consistent. I am thinking 500 or 600 yds for test should be sufficient to show any difference clearly.
 
#94
Re: Buffer spring effect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: longeye51</div><div class="ubbcode-body">I will use Federal SMK 168 grain with both springs. Other than possibly me, all other shooting conditions should be consistent. I am thinking 500 or 600 yds for test should be sufficient to show any difference clearly.</div></div>

This should be an interesting test.
 
#95
Re: Buffer spring effect on accuracy???

If one is going to attempt to be scientific, might be worth doing an A-B-A test. Original buffer spring, Tubb, original. Could even try the Tubb again for an A-B-A-B...just to try to account for variables like heat, etc.

I've got a pair of Tubb springs myself now. No time to test yet, and my one rifle is almost new. So, that one will be testing an almost new OEM spring against a new Tubb spring.
 
#96
Re: Buffer spring effect on accuracy???

I put one of these Tubbs srpings in my SDM rifle when I build it last year.

truly scientific would be a tested machine rest, same rifle, same ammo, same conditions and different springs.

it would be very interesting to see a high speed flouroscopic (xray movie) of the internals of AR in the firing process in a machine type rest to see exactly what mechanically occurs when in a timed sequence. this would settle many arguments I've read and explain a lot.

finally do believe the buffer, spring and bolt carrier do play a significant role as far as making AR's trickier to shoot than bolt. All three parts have mass and are in motion and generate internal force and momentum during firing sequence,that contribute with recoil to disturb muzzle alignment on target. I do believe these actions occur and exert effects before the bullet exits. Could a spring as a part of this mechanical system therefore affect it? Possibly. On the other hand on bolt gun the bolt is just dead and locked, and in and of itself alone the bolt as a part makes no similiar contribution of such internal forces to disturb the muzzle -- mechanically you're just dealing primarily with recoil.

Can't describe but I can tell when I've gotten a good shot off in my AR by the "feel" in recoil. Whoever could do this type of high speed motion xray could take that info and better define what it is you exactly have to do to "drive" an AR.
 
#97
Re: Buffer spring effect on accuracy???

I'd probably recommend a few more things to consider for any "test".

-Clean cold weapon for each string
-Time each string and shot so that each round remains in the chamber for approximately the same time

These things are critical when judging an auto and will ensure approximately equal and predictable temperature increases and pressure differentials during the strings
 
#98
Re: Buffer spring effect on accuracy???

As of today, I have the Tubb spring in hand. All the input is appreciated. I don't have a tested machine rest, so we're out of luck there. I will do an A-B-A-B-A-B test changing the spring and shooting 5 rounds each time. I will drive down and photograph the target between each test. That should help keep the heat consistent as well (although heat should not be a major issue as I will be using a stainless steel bull barrel and have no intent in heating it up). I will also keep the timing between rounds as consistent as possible.
 
#99
Re: Buffer spring affect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Kombar</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: RedCreek</div><div class="ubbcode-body">. So, assuming an AR was properly sprung to begin with, when that spring looses 10% of its efficiency and that loss yielded a 10% increase in carrier velocity this would in turn result in a 40% increase in energy of the carrier.
</div></div><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: RedCreek</div><div class="ubbcode-body">Its 40%

If you increase the velocity of an object you quadruple the engery and if you double the weight you only double the energy.

Speed x weight / 64.32 = energy

I would share with you the test results from a DoD project we did, but then I would have to kill you
shocked.gif


Show me your math...

-E </div></div>
First a list of variables used:
(F_sp = spring force, k = spring constant, s = spring displacement from equilibrium, a = acceleration, m = mass, v(s) = velocity as a function of position, v_0 = initial carrier velocity, v(s)_2 = carrier velocity when weak spring is used)

As for the part about a 10% increase in velocity:

F_sp = -k s

Once the rifle has fired and the carrier is moving rearward with velocity v_0, the acceleration of the carrier (neglecting friction) is:

a = F_sp/m = (-k s)/m

Integrate with respect to the position from spring equilibrium:

v(s)^2 = -k/m/2*s^2 + v_0^2

With a 10% loss in spring constant this becomes:

v(s)_2^2 = -.9k/m/2*s^2 + v_0^2

Divide out the 9/10, subtract the newly created remainder of v_0, substitute the identity for v(s)^2 into the v(s)_2^2 equation, move the remainder back, multiply back in the 9/10 and take the square root and you are left with:

--------------------------------------
v(s)_2 = sqrt(9/10*(v(s)^2+1/9*v_0^2))
--------------------------------------

This equation shows that the velocity of the carrier being controlled by the 10% weaker spring is dependent on the initial velocity of the carrier, and does not simply equal 10% more velocity than it would have had with a proper spring. This relationship was verified by computer model.


As for the second part of your post, kinetic energy is half the mass times velocity squared, so the original kinetic energy is m/2*v^2 (your equation would be correct for ft,lb,s units if you had remembered to square your velocity term). The kinetic energy of the carrier with the weakened spring is m/2*9/10*(v(s)^2+1/9*v_0^2). Again there is a dependency on the initial velocity, so it cannot be solved without initial conditions.

However, if the carrier velocity just so happens to be 10% greater than normal, energy would <span style="font-style: italic">still</span> not increase by 40%. The energy at 110% of an arbitrary velocity, v, is m/2*(1.10v)^2. Square that 1.10, and you are left with 1.21. At this point you can simply bring that out of the equation and you are left with the original energy calculation multiplied by 1.21. That is to say, for a 10% increase in velocity, there is a 21% increase in energy for any combination of mass and velocity.

You are getting confused with the definition of energy. Doubling, not just increasing, the velocity will quadruple the energy. </div></div>

Thank you,
I realized his error in math but just don't have the energy (or will) to respond in depth.
If you can't dazzle them with brilliance? (AKA competence in basic physics).................
Talking to Americans about matters of science and math is becoming sadly futile.
When I speak to folks from Europe I seriously seldom encounter what has become the norm here.
Even older engineers who do not stay sharp are disappointing because they will seldom believe that they are wrong and then want to analyze minutia to death.
What the hell is the matter with this country?
This shit is not that difficult if you graduated high school.
I can think of five different ways to prove the same thing, and they'll all be correct ways of looking at it (and I learned all but one way in high school).
We need to get our collective asses in gear, cause we're about to have Them handed to us.

This is not a bashing but a reality check.
We're all in the same sinking boat together.

To RedCreek
I F-up math all the time, it's what I do best.
I'm sure if this was an actual project and not a snipery post, you'd have identified the errors.

Only the steel in intimate contact with the buffer would be accelerated.
The reciprocating mass would achieve almost exactly the same velocity with no recoil spring.
A few grams of steel added to over 20 oz. of reciprocating mass will have a negligible effect for our discussion.
The carrier accelerates from zero to around 21 ft/sec (depending on recip mass) in less than 0.10"
The bullet has left the barrel after around 1 millisecond after pressure rise.

If the spring is indeed affecting accuracy, I would bet that it's an indirect cause/effect.

 
#100
Re: Buffer spring affect on accuracy???

Gee...I read something like that last post and people think this site is primarily bunch of infantry types who can't add and subtract.

The thread also reminds me as a kid growing up you are reminded there is always somebody meaner, and now as an adult i'm reminded there is always somebody smarter...

anyway maybe best taken offline as the topic is buffer spring, but could you engineers or somebody tell me exactly what mechanicially has occurred internally BEFORE the bullet has exited on gas system AR rifle (i.e., 5.56mm)? Like bolt has separated from barrel lugs, bolt assembly has moved rearward for distance x, so on.. thanks

 
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