Blitzkrieg Buffer ????

[MikieM]

Xanatos, I'll wager one of is wrong and I'm betting on you.

Regardless, I'm wore out from all this. I'm old and need my rest.

[Patrick Scott]

Got an answer from Kynshot.

[JAFO]

Seems like there would be a lot less energy to be dissipated on the return stroke, since it's only absorbing energy from the motion of the buffer mass at that point.

 

According to their claim, all of the piston movement takes place at the beginning of the recoil cycle.  That should mean that I'm still getting the full benefit out of it with a .308 rifle spring.  The recoil feels softer to me with that spring in.  It doesn't feel like the buffer is bottoming hard at the back of the tube.  I was wondering whether some of the compression was occurring when it impacted, and if I was missing out on some of the buffering by leaving that heavier spring in there.  I guess not.

[Xanatos903]

The buffer may only be ~1/4 of the weight of the whole system, but that's still 1/4 of the momentum that's slowed down over a greater length of time. And you're definitely right about getting the benefit of the .308 spring, even with the hydraulic buffer. 

 

Anyway, @MikieM, seems like the explanation for the Blitzkrieg's operation backs up what I'm saying about the Taccom. 

[MikieM]

40 minutes ago, Xanatos903 said:

The buffer may only be ~1/4 of the weight of the whole system, but that's still 1/4 of the momentum that's slowed down over a greater length of time. And you're definitely right about getting the benefit of the .308 spring, even with the hydraulic buffer. 

 

Anyway, @MikieM, seems like the explanation for the Blitzkrieg's operation backs up what I'm saying about the Taccom. 

 

Your statement is incorrect. The whole system, as you say, means the bolt and the buffer. Correct? Regardless, it has to mean the bolt and the buffer because they do not separate at any time during the cycle. They travel back and forth together.

Therefore, it's not 25 per percent of the momentum that is slowed but 100 per cent. The inference, of course, is that the hydraulic buffer is doing the slowing. I don't believe it is. 

In addition, the number wouldn't necessarily 25 per cent. It would all depend upon the action spring you were using. 

As for the Taccom, and others like it. They are nothing more than a spring within a spring. Why not simply use a spring with a higher rate to begin with?

[Xanatos903]

You're still misunderstanding how the buffer behaves. Read the last bullet point in Patrick's post and tell me that he isn't describing the buffer continuing forward after the bolt is already back in battery. 

 

And there's a lot to be said not only for a progressive spring rate, but also just a smoother operation. Like I've said, the normal buffer works just fine, the aftermarket buffers just do it smoother. 

[MikieM]

So you think that somewhere in the recoil cycle the bolt and buffer separate? 

 

"When the piston cap on the buffer hit's the retaining detent..."

Good grief Xanatos, you'd have to carry around a pocket full of detents as replacements.

Open your gun up then slowly close it back. If you watch closely you'll see the bolt and buffer just touch each other when the receivers are closed. All part of mil-spec.

[Patrick Scott]

23 minutes ago, MikieM said:

So you think that somewhere in the recoil cycle the bolt and buffer separate? 

 Id say the effective mass separates momentarily with hyd or Taccom/MBX style buffers, but obviously the parts do not physically separate.  Its really not that much different than a dead blow hammer. You are always swinging he same total weight,  but a certain points in the swing the internals effect the impact differently. 

Edited April 7, 2018 by Patrick Scott

[L9X25]

Help me understand this guys:

 

The instantaneous acceleration of the bolt collapses a 5lb spring, and associated hydraulic resistance, by pushing a 5oz buffer rearward against no resistance other than the weight of the buffer.  Then the buffer spring immediately starts slowing down the bolt, and the inertia of the buffer, combined with the 5lb springs pressure, do not extend the buffer back out before it strikes the back of the buffer tube?

 

Lets put this in terms that we are all familiar with.  I put you in the seat of my race car and accelerate full throttle for 1 second and then instantaneously kill the engine and slam on the brakes.  The instant I hit the brakes, the car starts decelerating rapidly and you are still pinned to the back of the seat?  What is holding you pinned to the seat?  Actually,  you will be pinned to the safety harness, and that would be the only thing keeping you off the dash board.   

 

In the case of the buffer, in addition to the rapid deceleration, there is a 5lb spring opening the buffer.  If it can close with inertia, against a spring, it will open with inertia when being helped by a spring.  To repeat, the buffer (excluding the rod and plate) weigh less than 5oz and the spring exerts 5 lbs of pressure.  

 

Am I missing something?

 

 

[Xanatos903]

Well I actually put a video together explaining what's going on with the Taccom buffer. Skip to 5:20 if you want to see my thinking on its function. Maybe this will clarify what I mean by decoupling the buffer from the bolt. 

 

 

[MikieM]

30 minutes ago, L9X25 said:

Help me understand this guys:

 

The instantaneous acceleration of the bolt collapses a 5lb spring, and associated hydraulic resistance, by pushing a 5oz buffer rearward against no resistance other than the weight of the buffer.  Then the buffer spring immediately starts slowing down the bolt, and the inertia of the buffer, combined with the 5lb springs pressure, do not extend the buffer back out before it strikes the back of the buffer tube?

 

Lets put this in terms that we are all familiar with.  I put you in the seat of my race car and accelerate full throttle for 1 second and then instantaneously kill the engine and slam on the brakes.  The instant I hit the brakes, the car starts decelerating rapidly and you are still pinned to the back of the seat?  What is holding you pinned to the seat?  Actually,  you will be pinned to the safety harness, and that would be the only thing keeping you off the dash board.   

 

In the case of the buffer, in addition to the rapid deceleration, there is a 5lb spring opening the buffer.  If it can close with inertia, against a spring, it will open with inertia when being helped by a spring.  To repeat, the buffer (excluding the rod and plate) weigh less than 5oz and the spring exerts 5 lbs of pressure.  

 

Am I missing something?

 

 

 

For clarification you consider the mass of the bolt and buffer as one. Correct?

I'm not so sure the race car analogy is a good one so let's just look at what we have.

 

When our guns fire the bolt and buffer travel rearward against the resistance of the action spring (buffer spring). If the spring isn't strong enough the bolt/buffer makes contact with the end of the spring tube and they stop. At that point the action spring has absorbed all of the kinetic energy available to it and begins releasing that stored energy to the bolt/buffer sending it in the opposite direction. They do not separate but travel together. If they did you would doubtless hear it and feel it. 

 

The question remains. Does the hydraulic buffer work? Does it work in one direction, or both. My belief is that it works (to a small extent) in the rearward movement of the bolt/ buffer only. The notion that it strikes the detent at the forward end of the tube and works again is ludicris. 

 

[L9X25]

You can't totally consider the bolt and buffer as one, since they are connected by a spring and they can move independently a certain distance.   

 

When you are sitting in a car, you are seat-belted in the seat but can move a small amount within the slack of the safety belts.  The analogy fits.

[Flatland Shooter]

1 hour ago, MikieM said:

 

Does the hydraulic buffer work? Does it work in one direction, or both. My belief is that it works (to a small extent) in the rearward movement of the bolt/ buffer only. The notion that it strikes the detent at the forward end of the tube and works again is ludicris. 

 

 

Compressing my Blitzkrieg buffer with just finger pressure and then rapidly releasing it shows that the amount of time for the piston to fully decompress is too long for it to be able to do so between multiple shots.  In a Bill drill (assuming decent splits) it would appear that the hydraulic buffer compresses for the first shot and stays compressed until after the sixth shot. 

 

Unless there is something in the mechanics of it all that I am missing?

 

It would be pretty simple for someone to remove the buffer retaining detent and see if there is any difference.

Edited April 7, 2018 by Flatland Shooter

[MikieM]

7 hours ago, Flatland Shooter said:

 

Compressing my Blitzkrieg buffer with just finger pressure and then rapidly releasing it shows that the amount of time for the piston to fully decompress is too long for it to be able to do so between multiple shots.  In a Bill drill (assuming decent splits) it would appear that the hydraulic buffer compresses for the first shot and stays compressed until after the sixth shot. 

 

Unless there is something in the mechanics of it all that I am missing?

 

It would be pretty simple for someone to remove the buffer retaining detent and see if there is any difference.

 

I hadn't considered multiple shots but on the face of it I think you're right. No stronger than the hydraulic buffer is it probably wouldn't decompress until the end of the string. If that is the case then it simply becomes another solid buffer. 

 

Thinking on it further, wouldn't the spring type buffer system act the same?

 

There was a thread a while back that addressed the issue of not using the retainer. It made closing the receiver a bit awkward but caused no problems regarding the function of the gun.

Edited April 7, 2018 by MikieM

[Xanatos903]

I don't think that the spring buffers would have the same problem- at least I don't think that the Taccom will. It's all dependent on the spring in the buffer being sufficiently stiff, but I think that the Taccom's is stiff enough to overcome the acceleration of the bolt/buffer system and re-extend the head while it's returning to battery. 

 

If the Blitzkrieg buffer can't do so it's not because of an inherent design flaw in buffers like this, but because of too much hydraulic damping. You can have the same problem when setting up a motorcycle's suspension- too much rebound damping and your suspension won't be able to accommodate the next bump you hit.

Edited April 7, 2018 by Xanatos903

[bmiller]

8 hours ago, Flatland Shooter said:

 

Compressing my Blitzkrieg buffer with just finger pressure and then rapidly releasing it shows that the amount of time for the piston to fully decompress is too long for it to be able to do so between multiple shots.  In a Bill drill (assuming decent splits) it would appear that the hydraulic buffer compresses for the first shot and stays compressed until after the sixth shot. 

 

Unless there is something in the mechanics of it all that I am missing?

 

It would be pretty simple for someone to remove the buffer retaining detent and see if there is any difference.

Bill, the buffer spring would be pushing in the forward portion of the hydraulic buffer when returning the bolt into battery.  In essence stretching the hydraulic buffer assembly out.  If you pull the buffer back apart, does it stretch out that a different rate than it compresses?  I do not have one to mess with.

[L9X25]

My AR15 has a pneumatic buffer as the ONLY means to return the BCG.  It is similar to a Blitzkrieg, except much larger with a longer stroke and stiffer internal spring.  It does not use an external buffer spring at all.  The unit feels a lot like a screen door regulator and dampens in both directions.   If you compress it with your fingers and release it, it takes longer than a blitzkrieg to fully extend.  Yet, in actual use, you can knock off .1 splits like clockwork.  How is that possible?  At the speed that our BCG travels, the buffer never bleeds off all of the internal pressure/vacuum and the remaining pressure/vacuum adds to the internal spring pressure to return the BCG to the closed position much faster.  The faster that the BCG travels, the more resistance and return pressure it provides. 

 

You cannot simulate what these devices are doing in your gun by compressing and releasing them with your finger.   While the blitzkrieg hydraulic mechanism does not appear to provide any resistance at the speeds we attain with our fingers, it is likely a different story when the bolt is attempting compressing them fully in .01 second. 

 

     

Edited April 7, 2018 by L9X25

[Xanatos903]

Very interesting points!

[MikieM]

I think the automotive reference you mean is the ELR (Emergency Locking Retractor) that only locks the seat belt during sudden stops, or collisions. 

If this comparison is accurate then the hydraulic buffer becomes solid during its travel back and forth.

My guess is the valving is so small that changing direction has no effect at all on it's compression and rebound.

 

Our blowback systems require far more buffering than does an AR15 delayed blowback.

[Startingover]

13 hours ago, Xanatos903 said:

Well I actually put a video together explaining what's going on with the Taccom buffer. Skip to 5:20 if you want to see my thinking on its function. Maybe this will clarify what I mean by decoupling the buffer from the bolt. 

 

 

Thanks 

Great vid and explanation 

[L9X25]

My pneumatic buffer is approved for use in a 9mm gun.  The only difference is that they request that you place the pneumatic cylinder so that it rotates with the buffer for 9mm, while they request that you place the pneumatic at the rear (non-reciprocating position) for .223.

 

In the .223 position, it is like a minimal weight buffer and it is much heavier in the 9mm position.

Edited April 7, 2018 by L9X25

[Xanatos903]

1 minute ago, Startingover said:

Thanks 

Great vid and explanation 

I'm glad you enjoyed the video!

 

 

[MikieM]

4 minutes ago, Xanatos903 said:

I'm glad you enjoyed the video!

 

 

 

I did too. Well done Xanatos.

I like it when we can have a spirited discussion without someone chiming in and calling someone else a "pompous grandstander".

[Xanatos903]

Yep, no reason to resort to name-calling. 

 

I'm still not completely convinced that there's not a better way to set up a PCC buffer, and I certainly haven't tried everything, but I do believe that the Taccom is a good out of the box improvement over the stock buffer setup. The fact that it comes in at significantly less than the Blitzkrieg doesn't hurt either. 

[L9X25]

In my automotive reference I was not alluding to any electronic trickery, merely the idea that two objects are loosely attached to where they generally move together while still having the ability to move freely with a short leash.  I also was attempting to describe the forces that act upon them, whereby they are either moving together or using their mass to offset the motion of the other.