Buffer spring effect on accuracy???

[Rovieairto]

Re: Buffer spring affect on accuracy???

I have that data if your really want to understand.
Sorry if I offended anyone, that wasn't my intention.
I am very much not the brightest bulb.

 

[longeye51]

Re: Buffer spring affect on accuracy???

No offense taken here. I am with you on your concerns about this country and math and science. It sounds like your high school math learning experience was much superior to mine, however. I do want to understand the data that you have, although I did not originally request it. So, please provide it to me as well.

 

[BattleAxe]

Re: Buffer spring affect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Guard Marksman</div><div class="ubbcode-body">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 </div></div>

I aint no genius but without a slide rule, calculator, or thesis, I'll say...

1. Shooter moves the crosshairs away from the target as he pulls the trigger. (except me of course

)
2. Hammer makes contact
3. Case expands momentarily and is pnuematically locked to the chamber walls (the bolt aint moving anywhere without taking a case rim with it)
4. Round accellerates while spinning imparting a torque force the weapon. (bolt still aint moving)
5. As the round passes the gas port, chamber pressure is instantly reduced and the locked case loses its death-grip on the chamber wall
6. Gas can now move the bolt rearward until the cam unlocks the bolt lugs

Without getting all scientific (no offense...just jerkin your chain). There aint no more mechanical stuff going on. The round has exited the bore before the spring even has time to realize...that it even is a freakin spring.

This should not be interpreted to mean that the spring doesn't work (accuracy-wise), just that I cannot grasp how it possibly could. Maybe its magic. Maybe I'm missing something.

 

[pupdawg]

Re: Buffer spring affect on accuracy???

Good run down BA.

So you feel that the round has exited the muzzle BEFORE the action starts to unlock?

I ask because I assume that the round may still be in the barrel while the action is unlocking (or moving)? Of course this would depend greatly on gas port location and barrel length ahead of the gas port. Or is this wrong?

I deduct that once the action starts to unlock, or once the bullet passes the gas port and chamber pressure drops you are also losing acceleration against the projectile. Which would explain the minimal velocity loss between a 20"/18" barrel with rifle length gas port?

ETA: If this is true then I can see the buffer assembly making a difference on some configurations of barrel length/gas system on the AR platform. IF in fact the bullet is still in contact with the barrel AT the time of OR during action movement.

I am curious.

 

[BattleAxe]

Re: Buffer spring affect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: pupdawg</div><div class="ubbcode-body">Good run down BA.

So you feel that the round has exited the muzzle BEFORE the action starts to unlock?

I ask because I assume that the round may still be in the barrel while the action is unlocking (or moving)? Of course this would depend greatly on gas port location and barrel length ahead of the gas port. Or is this wrong?

I deduct that once the action starts to unlock, or once the bullet passes the gas port and chamber pressure drops you are also losing acceleration against the projectile. Which would explain the minimal velocity loss between a 20"/18" barrel with rifle length gas port?

ETA: If this is true then I can see the buffer assembly making a difference on some configurations of barrel length/gas system on the AR platform. IF in fact the bullet is still in contact with the barrel AT the time of OR during action movement.

I am curious. </div></div>

Admittedly I'm guessing quite a bit but I'm good at figuring out how stuff works. As a kid if I couldn'y see inside something I'd fix that problem with a brick.

I don't believe the round is still in the bore as the lugs unlock. The bolt is prevented from moving rearward by recoil and it <span style="text-decoration: underline">has </span>to move rearwad to unlock the bolt via the cam pin.

As for minimal velocity change, the simplest explanation is the position of the gas block. If you think of the round as a valve (technically it is) that opens the gas port...a minimal amount of time expires between the "valve" opening in an 18 and 20 incher.

I can see an advantage IF in a rapid fire situation it improves movement of the bolt in concert with the buffer but good/smooth/accurate/whatever function doesn't equal accuracy. If that were the case I could take my forged Nike irons and make the PGA tour.

From purely an accuracy standpoint? The round is already gone and if somebody can prove me wrong I'll call myself a dumbass.

 

[pupdawg]

Re: Buffer spring affect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BattleAxe</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: pupdawg</div><div class="ubbcode-body">Good run down BA.

So you feel that the round has exited the muzzle BEFORE the action starts to unlock?

I ask because I assume that the round may still be in the barrel while the action is unlocking (or moving)? Of course this would depend greatly on gas port location and barrel length ahead of the gas port. Or is this wrong?

I deduct that once the action starts to unlock, or once the bullet passes the gas port and chamber pressure drops you are also losing acceleration against the projectile. Which would explain the minimal velocity loss between a 20"/18" barrel with rifle length gas port?

ETA: If this is true then I can see the buffer assembly making a difference on some configurations of barrel length/gas system on the AR platform. IF in fact the bullet is still in contact with the barrel AT the time of OR during action movement.

I am curious. </div></div>

Admittedly I'm guessing quite a bit but I'm good at figuring out how stuff works. As a kid if I couldn'y see inside something I'd fix that problem with a brick.

I don't believe the round is still in the bore as the lugs unlock. The bolt is prevented from moving rearward by recoil and it <span style="text-decoration: underline">has </span>to move rearwad to unlock the bolt via the cam pin.

I can see an advantage IF in a rapid fire situation it improves movement of the bolt in concert with the buffer but good/smooth/accurate/whatever function doesn't equal accuracy. If that were the case I could take my forged Nike irons and make the PGA tour.

From purely an accuracy standpoint? The round is already gone and if somebody can prove me wrong I'll call myself a dumbass. </div></div>

All that makes sense to me.

Except that if the round is clear of barrel contact before the action starts working then why is it that recoil management and follow through can make such a big difference on results downrange?

You and I both know that if you drive your AR platform like a bolt gun then the AR probably won't like you very much. Meaning, you fall asleep or alter your consistency with follow through on the AR and you throw your shot. Bolt guns are a lot more forgiving in this aspect... but why?

I want to know... I hope to shed some light on this topic for my sake cause it's been bugging me all friken week! haha

Maybe I should make a new topic??? idk

 

[BattleAxe]

Re: Buffer spring affect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: pupdawg</div><div class="ubbcode-body">Except that if the round is clear of barrel contact before the action starts working then why is it that recoil management and follow through can make such a big difference on results downrange? </div></div>

Because "driving the gun" is overrated (at least from my limited experience). Trigger squeeze and follow through on the trigger however is EVERYTHING when shooting a gas gun. I often don't "control" recoil/movement after the shot and still get off a good shot.

We often overlook the <span style="font-size: 17pt">HUGE</span> difference between an AR trigger and a good bolt gun trigger. Unless you're a freak show, you're absolutely going to move the rifle during trigger squeeze and follow through on a gas gun. You can either eliminate this movement...or duplicate it every single time. Your choice.

If you have access to SH's on-line training watch Jacob Bynum's lesson on gas guns and learn <span style="font-style: italic">some version</span> of his grip that feels right for you...then master it. Everything else you've ever learned about gas guns will become a footnote when you master your trigger.

 

[pupdawg]

Re: Buffer spring affect on accuracy???

I understand and agree 100% with what you said above in your 2nd paragraph.

I don't have access to the online training but have seen a video on Jacob's trigger manipulation and grip variation.
I should've put the word drive in quotes. But anyway...

I have no idea anymore about whether the bullet is outta the barrel or in the barrel when the action starts to move. (BA, I know what you think and I thank you for your input. thanks man.)

 

[SD26]

Re: Buffer spring affect on accuracy???

But isn't the unlocking of the bolt is still a function of the spring? Increase the rate enough, and one could make it so that the bolt would not unlock under the pressure of the round. Reduce the spring rate, and only a small amount of pressure sent down the gas tube will cause the bolt to unlock sooner.

How much distance does the bolt carrier move before the pressure is blown off down the gas tube?

 

[pupdawg]

Re: Buffer spring affect on accuracy???

Dave-

The unlocking of the bolt is (and don't quote me on this) as far as I understand a direct effect of the re-routed gas through the gas tube.

In other words the unlocking and movement of the bolt group has nothing to do directly with the buffer assembly, BUT the buffer assembly does inhibit the rearward travel and velocity of the bolt group.

Meaning the gas going back through the gas tube WILL move the bolt group back against the buffer weight/spring rate combination and you are correct in that a heavier buffer or higher spring rate will somewhat keep the bolt locked up a little longer.

Not that any of this will matter when we all go out to shoot, but for discussion sake.

 

[longeye51]

Re: Buffer spring affect on accuracy???

I have a 24" barrell. If I am understanding what your are saying correctly, due to the extra length of my barrell the bolt may start moving back before the bullet leaves the barrell. Is that correct? Or is the correllation the distance from the exiting end of the barrell to the gas tube,e.g., 18" barrell with the gas tube 8" from the exiting end of the barrell caises the bolt to begin to move backwards at the same time as a 24" barrell with the gas tube 8" from the exiting end of the barrell?

 

[pupdawg]

Re: Buffer spring affect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: longeye51</div><div class="ubbcode-body">I have a 24" barrell. If I am understanding what your are saying correctly, due to the extra length of my barrell the bolt may start moving back before the bullet leaves the barrell. Is that correct? Or is the correllation the distance from the exiting end of the barrell to the gas tube,e.g., 18" barrell with the gas tube 8" from the exiting end of the barrell caises the bolt to begin to move backwards at the same time as a 24" barrell with the gas tube 8" from the exiting end of the barrell? </div></div>

Yes this MIGHT be true. IF in fact as I said earlier the bullet is still in the bore.

With your 24" barrel there are microseconds of measurable dwell time of the bullet once it passes the gas port until it exits the muzzle.

There is also most likely a minimum amount of dwell time required to let the gas reciprocate into the gas tube and down into the bolt carrier. The gas will not do this reliably if the bullet relieves the chamber pressure (I'll just call it bore pressure) by exiting the muzzle before enough pressure has built up to cycle the bolt group against the buffer system.

So I also assume that this is obviously why a gas port located at rifle length (roughly 12" from the receiver) won't cycle a standard buffer/bolt carrier reliably with a barrel 13" long. (I assume because I have never tried it)

But what I initially was (and still am) curious about is say a 24" barrel (like yours) with a rifle length gas port lets just say 12" leaves another 12" of barrel for bullet "dwell time". Now assuming that the gas port pressure needs to be X PSI to unlock the action, does the gas port see that pressure while the bullet is still in the bore? It has to otherwise the action wouldn't unlock? Chamber pressure drops while the bleed off of pressure into the gas tube is happening otherwise you'd have failure to extract because the case would be pressed up against the chamber still.

So the action must be starting to move while the bullet is still in the bore and is unlocked as soon as the bullet ogive breaks the muzzle crown.

Idk, I'm hoping for someone to sum it up for me because I DONT KNOW for sure... I tried google but couldn't find anything saying something along the lines of "the bullet is in the bore while the action starts to move" or vice versa.

ETA: I have copy n pasted this to a new thread as not to derail this one anymore. Please join in there. http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=2846614#Post2846614

 

[Rovieairto]

Re: Buffer spring affect on accuracy???

SENSITIVITY STUDY OF RIFLE GAS SYSTEMS:
http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=AD0880431

The math and empirical data behind the M-16 and AR-18 gas systems.
They are both piston operated guns with very similar gas dynamics.
The piston chamber pressure has a far bigger delay in the M-16, but otherwise they are almost identical systems.

A STUDY OF PRESSURE TIME CURVES FOR SMALL CALIBER AMMUNITION:
http://dodreports.com/pdf/ada364826.pdf

More good data.
I have some excellent slow motion video that is worth more than these two studies.
The bullet is measurable in distance and therefor a handy time-line can be established for events to take place relative to the bullet's exit, Like how long pressure takes to reverse flow through the gas port etc....

 

[longeye51]

Re: Buffer spring affect on accuracy???

I completed the test today. It was a great day for shooting. Sunny, dry and very little wind. I have attached pictures of the 2 springs beside each other (Armalite and Tubb). The Tubb is approximately 1/3 longer than the stock Armalite. I also attached a picture of the rifle I use in the test.

I am a little rusty on my shooting, but that applies equally to all the shooting I did today. I have not shot since May due to the hot summer we had this year. After a few hundred yards there is an incredible mirage in 100+ degree heat, and anything short of that is not much of a challenge.

The first 2 A-B rounds I did today were with good shooting conditions. The last one was with quite a bit of mirage due to temperature rise. I can't blame the mirage for the high left shot with the Tubb spring on the 3rd round, I just pulled it.

I shot at 600 yds using Federal SMK 168 grain ammunition. I shot 6 total rounds (3 with each spring). I switched the springs out between each 5 shots. I cleaned the barrell between each round. I tried to keep the shot timing as consistent as possible.

It appears to me that the Tubb spring makes a pretty significant difference. The shots I made with the Tubb spring are all high because the gun is zeroed for the Armalite stock spring. When I shot a 3 shot group at 100 yards with the Tubb spring, the group was 1/2" in size. The best I have gotten with the Armalite spring is 5/8 of an inch. The 1/2" group was about 2 inches high which indicates to me that the Tubb spring is allowing the ammunition to get closer to its true ballistic potential. I am going to have to re-zero the gun for the Tubb spring.

I was surprised by the results. The pictures are attached below and are labeled by spring and round. On the later rounds, I circled the shots on the paper and blacked out the ones on the target so you can tell the difference between the old and new shots.

I do not know why it works better, but I am going to put Tubb springs in all my AR's. I was surprised by the results.

http://s1182.photobucket.com/albums...ket.com/albums/x446/sdennisx3/Tubb3600yds.jpg

 

[longeye51]

Re: Buffer spring effect on accuracy???

I apparently do not know how to download pictures from photobucket. Can someone help me out?

 

[longeye51]

Re: Buffer spring effect on accuracy???

I completed the test today. It was a great day for shooting. Sunny, dry and very little wind. I have attached pictures of the 2 springs beside each other (Armalite and Tubb). The Tubb is approximately 1/3 longer than the stock Armalite. I also attached a picture of the rifle I use in the test.

I am a little rusty on my shooting, but that applies equally to all the shooting I did today. I have not shot since May due to the hot summer we had this year. After a few hundred yards there is an incredible mirage in 100+ degree heat, and anything short of that is not much of a challenge.

The first 2 A-B rounds I did today were with good shooting conditions. The last one was with quite a bit of mirage due to temperature rise. I can't blame the mirage for the high left shot with the Tubb spring on the 3rd round, I just pulled it.

I shot at 600 yds using Federal SMK 168 grain ammunition. I shot 6 total rounds (3 with each spring). I switched the springs out between each 5 shots. I cleaned the barrell between each round. I tried to keep the shot timing as consistent as possible.

It appears to me that the Tubb spring makes a pretty significant difference. The shots I made with the Tubb spring are all high because the gun is zeroed for the Armalite stock spring. When I shot a 3 shot group at 100 yards with the Tubb spring, the group was 1/2" in size. The best I have gotten with the Armalite spring is 5/8 of an inch. The 1/2" group was about 2 inches high which indicates to me that the Tubb spring is allowing the ammunition to get closer to its true ballistic potential. I am going to have to re-zero the gun for the Tubb spring.

I was surprised by the results. The pictures are attached below and are labeled by spring and round. On the later rounds, I circled the shots on the paper and blacked out the ones on the target so you can tell the difference between the old and new shots.

I do not know why it works better, but I am going to put Tubb springs in all my AR's. I was surprised by the results.

 

[pupdawg]

Re: Buffer spring effect on accuracy???

Longeye -

Nice shooting!

How does the recoil impulse feel between the two springs in your opinion?

I have a tubb spring in my Armalite AR10T but I am waiting on my Krieger M110 barrel to come in so I can try it out. I have a tubb spring in my AR15 and it works well.

 

[Jeepocabra]

Re: Buffer spring effect on accuracy???

Any comment on the feel of the spring in the rifle? Did it feel like it was slamming the bcg in harder than the other spring?

 

[Sebben]

Re: Buffer spring affect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BattleAxe</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: pupdawg</div><div class="ubbcode-body">Except that if the round is clear of barrel contact before the action starts working then why is it that recoil management and follow through can make such a big difference on results downrange? </div></div>

Because "driving the gun" is overrated (at least from my limited experience). Trigger squeeze and follow through on the trigger however is EVERYTHING when shooting a gas gun. I often don't "control" recoil/movement after the shot and still get off a good shot.

We often overlook the <span style="font-size: 17pt">HUGE</span> difference between an AR trigger and a good bolt gun trigger. Unless you're a freak show, you're absolutely going to move the rifle during trigger squeeze and follow through on a gas gun. You can either eliminate this movement...or duplicate it every single time. Your choice.

If you have access to SH's on-line training watch Jacob Bynum's lesson on gas guns and learn <span style="font-style: italic">some version</span> of his grip that feels right for you...then master it. Everything else you've ever learned about gas guns will become a footnote when you master your trigger. </div></div>


This is exactly the difference between Gas guns and bolt guns. Even if the action is moving while the bullet is still in the bore. This is negligible due to the fact that the small amount the BCG moves is lateral movement. The trigger follow through is very important due to the time it takes for the hammer to release and strike the firing pin. As you press the trigger to the rear the hammer is in motion on its way to say hello to its friend Mr. Firing pin. So you must consistently be able to apply pressure straight back on the trigger as the hammer is in motion. AKA follow through. When compared to a bolt gun where there is no hammer and the firing pin is driven by spring and is almost directly released by the trigger. So the time that follow through counts on a bolt gun is less than it is with a hammer fired weapon.

As stated before. Once you pull the trigger. Or what should be said is; once the hammer strikes the firing pin which strikes the primer you are only along for the ride. So there is absolutely nothing your body can do to throw off the shot once the primer is stuck and the chain of events known as firing has started.

To fully understand how fast this happens. one needs to compare it to something of known speed. It takes the human eye 300-400ms to blink. It takes a bullet from the time the primer is struck to the time the bullet leaves the barrel 2ms. That's fast as shit!

 

[BattleAxe]

Re: Buffer spring affect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Sebben</div><div class="ubbcode-body">Once you pull the trigger. Or what should be said is; once the hammer strikes the firing pin which strikes the primer you are only along for the ride. So there is absolutely nothing your body can do to throw off the shot once the primer is stuck and the chain of events known as firing has started.

To fully understand how fast this happens. one needs to compare it to something of known speed. It takes the human eye 300-400ms to blink. It takes a bullet from the time the primer is struck to the time the bullet leaves the barrel 2ms. That's fast as shit! </div></div>

This is the part that people refuse to grasp. If you were to time the firing sequence from the start of the trigger squeeze until the round clears the muzzle you'd likely come up with a number somewhere around one second. During that 1 second there's a dumb human squeezing the rifle for likely 90% or more of that second, yet they're looking for all sorts of other reasons to explain the difference between a gas and bolt gun.

It's OK to admit that your trigger squeeze and follow through suck. Admitting it will set you free and take your shooting to a whole other level. It will also spare you drain on your wallet that comes from throwing parts at an otherwise perfectly functioning weapon.

 

[rsilvers]

Re: Buffer spring effect on accuracy???


It would take a lot of rounds to prove a difference.

 

[longeye51]

Re: Buffer spring effect on accuracy???

Pupdawg and Jeepocabra,

To tell you the truth, I was paying so much attention to trying to keep everything consistent between the test of the 2 springs that I did not notice. As I think about it now, it did seem like the gun did not jump off target after firing as much with the Tubb spring. As fot the return of the bolt, I don't know.

 

[Rovieairto]

Re: Buffer spring effect on accuracy???

Thanks for the time and effort you put into your posts.
Because of your test I'm going to buy that damned Tubb spring after all.
If it helps my rifle it'll bug the crap out of me until I find out why.
Your results definitely make this worth a try.
I blow thousands of dollars on ammunition, this would be a bargain.

 

[-=boone=-]

Re: Buffer spring effect on accuracy???

I purchased a tubbs spring and went shooting this weekend. Gun was much more consistent and felt a lot better.

 

[KevinB-KAC]

Re: Buffer spring effect on accuracy???

I run a Tubb spring, - but irrelevant to that issue, if you look at high speed video - the bullet is gone before the carrier starts rearward movement.
It cannot and does not affect mechanical accuracy.

It may make you more comfortable, and quite often in weapons, its the nut behind the bolt that is the biggest factor in that.

 

[longeye51]

Re: Buffer spring effect on accuracy???

Hamilton,

I have been advised that my test is scientifically insufficient, inconclusive and that my opinions are premature at best and probably without basis. That being said, don't spend $30 on my account. I do not want anyone to spend unnecessary money in these times based on what I have been advised is insufficient testing.

If you do decide to buy one, do it because you want to try it for yourself. If you buy one, please let me know how it works for you. I would like to know if your experience is the same as what I "think" mine was.

 

[Rovieairto]

Re: Buffer spring effect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: KevinB-KAC</div><div class="ubbcode-body">I run a Tubb spring, - but irrelevant to that issue, if you look at high speed video - the bullet is gone before the carrier starts rearward movement.
It cannot and does not affect mechanical accuracy.

It may make you more comfortable, and quite often in weapons, its the nut behind the bolt that is the biggest factor in that.

</div></div>
What I learned from high speed video is that the carrier definitely starts its rearward acceleration before the bullet has left the barrel.
The pressure spike seems to occur after the bullet has left, however it will begin accelerating as soon as it experiences an imbalance of forces.
According to the document I provided the delay has to do with gas inertia and port size/location.

Is gas going into the gas tube, and ultimately the piston chamber immediately after the bullet passes the gas port?
Yes, it absolutely will...... why wouldn't it?
Is pressure going to build in the piston chamber while the bullet is still in the barrel?
If it didn't, what would make the gas go there AFTER the pressure has dropped in the barrel?

Will this pressure exert force?
Yes.

We all should know what happens when an imbalance of forces exists.
Acceleration.

Therefor it must begin accelerating while the bullet is still in the barrel.
There will exist an imbalance of forces unless you can tell be where the equal, but opposite force preventing acceleration comes from from, and why it lets go only after the bullet clears the muzzle?

 

[Rovieairto]

Re: Buffer spring effect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: longeye51</div><div class="ubbcode-body">Hamilton,

I have been advised that my test is scientifically insufficient, inconclusive and that my opinions are premature at best and probably without basis. That being said, don't spend $30 on my account. I do not want anyone to spend unnecessary money in these times based on what I have been advised is insufficient testing.

If you do decide to buy one, do it because you want to try it for yourself. If you buy one, please let me know how it works for you. I would like to know if your experience is the same as what I "think" mine was. </div></div>

LOL.
It would be difficult to prove that the earth is a sphere.

I'm buying it because of your test.
I do not see how it could possibly have an effect, but I'll give it a go.
I'm not one to argue with what is.
I will accept the results for what they are.

Again, thanks.

 

[BattleAxe]

Re: Buffer spring effect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Hamilton</div><div class="ubbcode-body">There will exist an imbalance of forces unless you can tell be where the equal, but opposite force preventing acceleration comes from from, and why it lets go after the bullet clears the muzzle?


</div></div>

Recoil

 

[Rovieairto]

Re: Buffer spring effect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BattleAxe</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Hamilton</div><div class="ubbcode-body">There will exist an imbalance of forces unless you can tell be where the equal, but opposite force preventing acceleration comes from from, and why it lets go after the bullet clears the muzzle?


</div></div>

Recoil </div></div>

recoil+?

OK, please explain.

 

[BattleAxe]

Re: Buffer spring effect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Hamilton</div><div class="ubbcode-body">recoil+?

OK, please explain. </div></div>

Simple physics.

A body at rest stays at rest. The carrier is at rest. The rifle is moving violently rearward and traps the carrier forward regardless of whatever pressures it may see.

That's just a guess but the 1st time you take an ocular to the forehead because you didn't hold on you'll see the logic behind it.

 

[Rovieairto]

Re: Buffer spring effect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BattleAxe</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Hamilton</div><div class="ubbcode-body">recoil+?

OK, please explain. </div></div>

Simple physics.

A body at rest stays at rest. The carrier is at rest. The rifle is moving violently rearward and traps the carrier forward regardless of whatever pressures it may see.

That's just a guess but the 1st time you take an ocular to the forehead because you didn't hold on you'll see the logic behind it. </div></div>

Cool, I learned something today.
You're right.
I seriously didn't think of that.

However it is not regardless of pressure.
It requires that the recoiling rifle always be accelerating at a faster rate that the carrier wants to.
Imagine a 1000 lb. 223 rifle barrel with standard weight carrier, and a muzzle break.
The rifle will accelerate at practically zero ft./sec so recoil's acceleration would not be present to hold the carrier firmly against the barrel.

 

[Sebben]

Re: Buffer spring effect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Hamilton</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BattleAxe</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Hamilton</div><div class="ubbcode-body">recoil+?

OK, please explain. </div></div>

Simple physics.

A body at rest stays at rest. The carrier is at rest. The rifle is moving violently rearward and traps the carrier forward regardless of whatever pressures it may see.

That's just a guess but the 1st time you take an ocular to the forehead because you didn't hold on you'll see the logic behind it. </div></div>

Cool, I learned something today.
You're right.
I seriously didn't think of that.

However it is not regardless of pressure.
It requires that the recoiling rifle always be accelerating at a faster rate that the carrier wants to.
Imagine a 1000 lb. 223 rifle barrel with standard weight carrier, and a muzzle break.
The rifle will accelerate at practically zero ft./sec so recoil's acceleration would not be present to hold the carrier firmly against the barrel. </div></div>

So is the BCG moved completely by gas system or is it also moved by the recoil of the round?

 

[BattleAxe]

Re: Buffer spring effect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Hamilton</div><div class="ubbcode-body">[However it is not regardless of pressure.</div></div> True, I was oversimplifying for discussion sake.

 

[BattleAxe]

Re: Buffer spring effect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Sebben</div><div class="ubbcode-body">So is the BCG moved completely by gas system or is it also moved by the recoil of the round? </div></div>

Recoil pulse is has largely subsided by the time the bolt unlocks. Its moved by gas.

 

[Erud]

Re: Buffer spring effect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Hamilton</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BattleAxe</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Hamilton</div><div class="ubbcode-body">recoil+?

OK, please explain. </div></div>

Simple physics.

A body at rest stays at rest. The carrier is at rest. The rifle is moving violently rearward and traps the carrier forward regardless of whatever pressures it may see.

That's just a guess but the 1st time you take an ocular to the forehead because you didn't hold on you'll see the logic behind it. </div></div>

Cool, I learned something today.
You're right.
I seriously didn't think of that.

However it is not regardless of pressure.
It requires that the recoiling rifle always be accelerating at a faster rate that the carrier wants to.
Imagine a 1000 lb. 223 rifle barrel with standard weight carrier, and a muzzle break.
The rifle will accelerate at practically zero ft./sec so recoil's acceleration would not be present to hold the carrier firmly against the barrel. </div></div>

Hey Hamilton,

You're blinding me - with science!

 

[Rovieairto]

Re: Buffer spring effect on accuracy???

I watched the video again and I've been mistaken.

Well the video I have is of a carbine in a lead sled.
So I went to calculating.
The time-lines are such:
0.0-0.60 ms to gas port, 0.0 - 0.90 ms to muzzle.
The bolt carrier acceleration starts at 0.76 ms and roughly ends at 3.6 ms
With a consistently observed 0.2 ms delay in cavity pressure rise for the rifle length gas system shown in SENSITIVITY STUDY OF RIFLE GAS SYSTEMS.pdf
I calculate 0.16 ms delay for the carbine.
If that's true that leaves only 0.14 ms for the pressure to rise enough for the carrier's acceleration to exceed that of the rifle's.
Every combination I tried (except my rifle in the lead lead) gave me accelerations that began only after the bullet leaves the barrel, and the rifle's rearward acceleration ends.
The lead sled combo should have the carrier moving 0.11 ms before bullet exit, although it looks a tad later than that on the video.
That is a very small amount of time anyhow.
Even the 1000 lb rifle should only only see just less than 0.14 ms overlap at most.

 

[sf88]

Re: Buffer spring effect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BattleAxe</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Sebben</div><div class="ubbcode-body">So is the BCG moved completely by gas system or is it also moved by the recoil of the round? </div></div>

Recoil pulse is has largely subsided by the time the bolt unlocks. Its moved by gas. </div></div>

This is why when you turn off the gas system on 556 guns with an "off" adjustment on the gas block the carrier does not move.

 

[Rovieairto]

Re: Buffer spring effect on accuracy???

I would say that the carrier is accelerated a little by the rifle and a lot by the gas.
The 3 ft/sec (about 1/50th the cycle energy required) it may get through recoil is resisted, and brought back into place quickly by the recoil spring.
The Benelli inertia system relies on rearward rifle acceleration to compress a sprung mass (carrier) that then "bounces" off the rifle.
The Newtonian maximum would be 2x the rearward velocity of the rifle.
A ball never bounces higher than it's dropped.
With a lightweight shotgun, this works beautifully.

 

[Sebben]

Re: Buffer spring effect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Hamilton</div><div class="ubbcode-body">I would say that the carrier is accelerated a little by the rifle and a lot by the gas.
The 3 ft/sec (about 1/50th the cycle energy required) it may get through recoil is resisted, and brought back into place quickly by the recoil spring.
The Benelli inertia system relies on rearward rifle acceleration to compress a sprung mass (carrier) that then "bounces" off the rifle.
The Newtonian maximum would be 2x the rearward velocity of the rifle.
A ball never bounces higher than it's dropped.
With a lightweight shotgun, this works beautifully.
</div></div>

On my POF if i turn the Gas off the felt recoil impulse changes drastically. But I think the BCG still moves slightly. ill have to have some one else shoot it and watch. I'll video tape it. Hell I'll even take the piston system out.

 

[longeye51]

Re: Buffer spring effect on accuracy???

I understand that theory, but usually you have the gun against a solid object (your shoulder). Usually, you do not take on ocular to the forehead. What then?

 

[BattleAxe]

Re: Buffer spring effect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: longeye51</div><div class="ubbcode-body">I understand that theory, but usually you have the gun against a solid object (your shoulder). Usually, you do not take on ocular to the forehead. What then? </div></div>Your shoulder isn't as solid as you think. The rifle will move. You're not strong enough or fast enough to stop it.

 

[KevinB-KAC]

Re: Buffer spring effect on accuracy???

Its a rotating locking bolt weapon, the bolt is not moved by recoil/pressure from the round*
It unlocks from the pressure of the gasses on the piston (yes the AR has a piston, its the tail of the bolt) that expand and push the carrier rearward, which in turn unlocks the bolt.

*Now when there is a suppressor attached, the additional backpressure will acton the casing and push the carrier rearward with greater speed.

 

[pupdawg]

Re: Buffer spring effect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Sebben</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Hamilton</div><div class="ubbcode-body">I would say that the carrier is accelerated a little by the rifle and a lot by the gas.
The 3 ft/sec (about 1/50th the cycle energy required) it may get through recoil is resisted, and brought back into place quickly by the recoil spring.
The Benelli inertia system relies on rearward rifle acceleration to compress a sprung mass (carrier) that then "bounces" off the rifle.
The Newtonian maximum would be 2x the rearward velocity of the rifle.
A ball never bounces higher than it's dropped.
With a lightweight shotgun, this works beautifully.
</div></div>

On my POF if i turn the Gas off the felt recoil impulse changes drastically. But I think the BCG still moves slightly. ill have to have some one else shoot it and watch. I'll video tape it. Hell I'll even take the piston system out. </div></div>

With the gas system off the AR basically becomes a bolt action rifle.

The bolt can't move because the buffer spring is pushing forward on the carrier and the locking lugs on the bolt are locked into the barrel extension lugs.

 

[Afghanvet09]

Re: Buffer spring effect on accuracy???

sebben with gas turned off and what you've described (e.g., recoil pulse), wonder how different the rifle shoot/group (feeding 1 round at time) with gas off verses on and autofeed?

 

[Sebben]

Re: Buffer spring effect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Guard Marksman</div><div class="ubbcode-body">sebben with gas turned off and what you've described (e.g., recoil pulse), wonder how different the rifle shoot/group (feeding 1 round at time) with gas off verses on and autofeed? </div></div>

well I guess the next time I go to the range I will find out. But one of the first things I need to do is put glass on my rifle. I'm waiting for some stuff to come in so I can buy a scope mount. I have a champagne taste with a beer budget...

 

[longeye51]

Re: Buffer spring effect on accuracy???

I found out Tubbs' CWS system works in an AR-15 bolt as well as an AR-10 bolt. I have one on order. I am going to try it in conjunction with the Tubb AR-10 spring and see what happens. I'll let you know how it works. I'll try to pay attention to the feel of the recoil this time as well.

 

[HPLLC]

Re: Buffer spring effect on accuracy???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: KevinB-KAC</div><div class="ubbcode-body">Its a rotating locking bolt weapon, the bolt is not moved by recoil/pressure from the round*
It unlocks from the pressure of the gasses on the piston (yes the AR has a piston, its the tail of the bolt) that expand and push the carrier rearward, which in turn unlocks the bolt.

*Now when there is a suppressor attached, the additional backpressure will acton the casing and push the carrier rearward with greater speed.

</div></div>

I know this thread is really old, but I was over at Brownells doing the thing I do every time I'm done with an order (try to anticipate the part I'll want to buy next so I can buy it now instead), and I looked at the Tubb spring for the 3-4 time.

I decided to buy it and try it out later (like 1-2 months from now).

I did that because the tubb spring video (below) where the guy talks about the spring, suggests that the normal spring is getting weaker with every round, where the Tubb spring is not.

<span style="font-weight: bold">So at the very least, consistency over time and rounds fired is improved. </span>

They also mentioned how the bolt would stay locked longer due to increased pressure in the locked position, but would also cycle slower on rebound from fully rearward in the tube.

I've noticed a tendency of guys to single load rounds from slide lock when trouble shooting autoloaders. This tends to suggest that bolt rebound velocity is inconsistent and there may be minor differences in bolt attitude from round to round that contribute to accuracy problems. Or that people are paranoid and superstitious. One, the other or a combination of both.

For improved accuracy I was thinking that potentially the locking of the rifle could be more consistent round to round.

I also read a post of a guy who claimed his cases were 75% less dirty with the Tubb spring as opposed to the OEM. That suggested enhanced dwell.

<span style="font-weight: bold">At any rate due to the fact that David Tubb has for whatever reason not chosen to make any statements about the potential accuracy benefits of the product, I figured buying one would be the only way to know if it would help in my rifle. </span>

The guy in this thread who seems to show an improved accuracy from a $20 spring swap is interesting. Even 5% improved accuracy would be worth $22.

[video:youtube]https://www.youtube.com/watch?v=lZQUYGbGmr4[/video]

 

[DTubb]

Re: Buffer spring effect on accuracy???

Griffin,
PM me your address and I will ship you a Flatwire with a Sandstrom 28A coating. It is a permanent dry lub and makes the buffer spring even quieter. More than likely this coating will be integrated into our Chrome Silicon spring products.
I am guessing you would like a 36 coil?

Regards,
DTubb

 

[luckyshot27]

Re: Buffer spring effect on accuracy???

just bought one..going to see if there are any differnces..