Buffer question

[Bksrt8]

I was pondering the other day, while looking at some pellet guns, has a nitro piston buffer ever been used or even tried for AR platforms? Would there be any benefit over the spring style buffers? Maybe it could be physically smaller for pistol type guns to allow various stock types?
Just thinking out loud, I did a very (VERY) quick Google search but didn't find anything before adhd kicked in and I forgot what I was doing.

 

[mmattockx]

I was pondering the other day, while looking at some pellet guns, has a nitro piston buffer ever been used or even tried for AR platforms?

You mean using a pressurized gas as the spring instead of a metal spring? I don't know of any, but I will say most of the time gun designers want springs that aren't very progressive in the force they produce and that is the opposite of what a gas spring does. Gas springs are highly progressive and rapidly ramp up their force output through their travel.


Mark

 

[Bksrt8]

So what you want is consistent force then? Would it not help on guns with a short buffer tube? You could get the force required without some giant heavy spring....im just spitballing here, Im just an idiot with a PAL. I know guns go bang, thats about it lol

 

[Ex3dy]

diemaco made a hydraulic buffer but kept the traditional recoil spring, kynshot makes a similar product.
the cost and complications would likely make gas springs commercially unviable.

 

[mmattockx]

So what you want is consistent force then? Would it not help on guns with a short buffer tube? You could get the force required without some giant heavy spring....im just spitballing here, Im just an idiot with a PAL. I know guns go bang, thats about it lol

Not consistent, just not a big increase in force. If you go through firearms design texts you will find that what works best is a fair amount of preload on the spring, so that it forces the bolt closed and holds it there and also that the spring rate is fairly low, so that there isn't a massive increase on the bolt forces as the action cycles so it can cycle properly (bolt travel and velocity) and isn't too hard to manually operate the action.

When you look at the design equations there is a fairly small window of what works properly in all aspects. It would be hard to get the desired characteristics from a gas spring setup.

diemaco made a hydraulic buffer but kept the traditional recoil spring, kynshot makes a similar product.

That isn't the same at all, though. A hydraulic buffer just absorbs energy, it doesn't return it back into the action the way a spring does.

Mark

 

[Gunnerlove]

I doubt gas would give you consistent force from -40C to +40C

 

[Ex3dy]

That isn't the same at all, though. A hydraulic buffer just absorbs energy, it doesn't return it back into the action the way a spring does.

Mark

I think we may be having some terminology or conceptual confusion, are we talking about replacing the recoil spring, the tungsten filled buffer or both with a pre charged gas cylinder?

 

[mmattockx]

I think we may be having some terminology or conceptual confusion, are we talking about replacing the recoil spring, the tungsten filled buffer or both with a pre charged gas cylinder?

I believe OP is talking about replacing the coil recoil/main spring with a gas spring, such as the cylinder you describe.


Mark

 

[I Dont Care About You]

Aside from the problems with spring rates, consider for a second, how you are going to contain a pressurized gas over thousands upon thousands of cycles in a system that involves fine dirt and grit that is forced into the smallest of spaces. This is a non-trivial problem that would likely weigh more than a simple spring and be way less reliable.

SA guns have been in use for over 100 years. There is a reason they all use simple springs.

 

[mmattockx]

Aside from the problems with spring rates, consider for a second, how you are going to contain a pressurized gas over thousands upon thousands of cycles in a system that involves fine dirt and grit that is forced into the smallest of spaces. This is a non-trivial problem that would likely weigh more than a simple spring and be way less reliable.

The spring doesn't get that dirty, though. Motorcycle shocks operate in a similarly dirty environment (especially off road bikes) and they carry a nitrogen charge for years of service, which would entail many thousands of cycles as well. I think the problem is likely solvable, but very much non-trivial, as you say.

SA guns have been in use for over 100 years. There is a reason they all use simple springs.

Yep. Springs are a solved problem in terms of manufacturing and metallurgy and they do the job with few problems.


Mark

 

[OkayShooter]

Likely because gas struts take more force to compress. Force to absorb the recoil, may not have enough force the return bolt back into battery.

 

[BullOnParade]

Aside from the problems with spring rates, consider for a second, how you are going to contain a pressurized gas over thousands upon thousands of cycles in a system that involves fine dirt and grit that is forced into the smallest of spaces. This is a non-trivial problem that would likely weigh more than a simple spring and be way less reliable.

SA guns have been in use for over 100 years. There is a reason they all use simple springs.

Nitrogen cylinders are common place in stamping dies, flooded with cutting coolant, dirt and oils, metal dust, dirt and other debris. I don’t think the environment in a buffer tube could even come close to where I see nitrogen cylinders used.

 

[Gunnerlove]

-40. To +40

Springs don't care.

 

[Bksrt8]

Sorry I didn't realize anybody else had replied here.
I am asking about if anyone (not backyard Bubba but a legit gun builder/company) has ever tried replacing the buffer, weight and return spring with a gas piston system. And what would the benefits/negatives be of such a system.
As far as the gas not liking the extreme cold, nitrogen filled shocks are commonly used in the arctic/extreme climates....you generally dont see a fluid filled shock absorber used in extreme climates anymore because the fluids tend to freeze or change viscosity. Nitrogen is commonly used in shocks and recently to replace air in your tires because it is much more stable in extreme climate compared to air. As long as the pressurized cylinder doesnt leak, you will maintain constant(ish) pressure in any weather. It shouldnt wear out like a spring could, I do realize that the springs are very reliable, its a simple and reliable system. A gas buffer system could introduce new reliability issues.
As far as being harder to operate ei: cycle the action, I mean, its easy enough to just not pressurized the gas cylinder as much as you might for a pellet gun application...and if you add a Schrader valve somewhere you could easily fine tune the pressure.
Im not an engineer, Ive never been to gunsmithing school, I spent a year in Army Cadets when I was 16 and only finally got my PAL 2 years ago, i just like guns more than most people and im curious. Thanks again for the replies!

 

[mmattockx]

As far as the gas not liking the extreme cold, nitrogen filled shocks are commonly used in the arctic/extreme climates....you generally dont see a fluid filled shock absorber used in extreme climates anymore because the fluids tend to freeze or change viscosity. Nitrogen is commonly used in shocks and recently to replace air in your tires because it is much more stable in extreme climate compared to air.

Any shock that offers actual damping has fluid in it. The nitrogen is just used to keep the fluid pressurized to minimize cavitation during operation.

Nitrogen is not significantly more pressure/temperature stable than air, it is used in tires because it is very dry, which reduces temp induced pressure swings. If you had compressed air that was equally as dry it would be just as stable because it's the moisture that causes the big pressure variations. Nitrogen also leaks out a bit slower than air, so it holds pressure longer than an air filled tire.

As far as being harder to operate ei: cycle the action, I mean, its easy enough to just not pressurized the gas cylinder as much as you might for a pellet gun application.

No, you misunderstand. You need a minimum amount of force on the closed bolt to keep it closed and ensure reliable operation. That cannot be reduced or reliability suffers. Because a gas cylinder is very non-linear in its spring rate it would be hard to get easy manual operation combined with that initial preload force. This is also a problem in springs, it is just easier to work around it with their linear spring rates.


Mark

 

[Bksrt8]

Could you not then use a shock fluid as a damper in the buffer system and still maintain enough pressure to keep the bolt closed without being too much to operate? Its going to have a minimum pressure no matter what right? So if you used a damper like a shock has you can control the force/speed that the gas piston moves while still maintaining that minimum pressure at the end of the piston stroke? Again, spitballing here, clearly not an engineer lol

 

[mmattockx]

Could you not then use a shock fluid as a damper in the buffer system and still maintain enough pressure to keep the bolt closed without being too much to operate? Its going to have a minimum pressure no matter what right? So if you used a damper like a shock has you can control the force/speed that the gas piston moves while still maintaining that minimum pressure at the end of the piston stroke? Again, spitballing here, clearly not an engineer lol

That is a detail design question. I expect that something could be worked out, but it will be more complicated and costly than a simple spring system that is already proven.


Mark

 

[Bksrt8]

That is a detail design question. I expect that something could be worked out, but it will be more complicated and costly than a simple spring system that is already proven.


Mark

I was also beginning to think that. How much better could it possibly be over what we already have? And at what cost? The thing has been around since the 60s/70s without much need for change.