Noise Level: .30 Cal vs .22 Cal

[subscriber]

So, we have a test result for the Notos inspired LDC that was printed overnight - see screen captures below.

This was on a .22 Air Max Dominator - I have asked Mike what his pellet weight and velocity were. EDIT: Mike provided the info: "Crosman hp 14.3 825fps" That is 21.6 FPE.


Mike's test results: https://www.gatewaytoairguns.org/GTA/index.php?topic=208202.msg156450525#msg156450525

Oh, and I emailed the STL files to Stubbers, so he can make his own assessment. He is a skeptic, as he should be. If any result is real, then it should be easy to repeat.

80% of success is managing expectations. Considering my designs are a gift to the airgun community, if you have a 3D printer and low expectations, you might get surprisingly good value for money trying one of these.

I will see if I can encourage Mike (or anyone else, please) to test this LDC at 12 FPE to assess if the hammer drop can be heard over the muzzle blast when shooting it. That is the claim two Notos owners have made about it.

As for mouse fart quiet; I have never heard one, so can't use it as any kind of measure. A bit like the length of a unicorn horn.

 

[Headshots]

The Impact has a hammer that’s well enclosed and relatively distal to the shooters ear. For me, that’s the main advantage over the Maverick and wildcat, which can get pretty obnoxious at higher power levels. Many people cite the Taipan Vets as the models for quietness, but in my experience the Impact is quieter, fpe for fpe.

I have a Veteran Standard and a 600mm Maverick. The Vet is far quieter. And less noise from the shot cycle.

 

[Sanctify7]

As stated above .. so subjective to tune, valve type etc ...
I personally have a 90fpe .30 that is so quiet it does not need an LDC, just mild a Th whop sound at muzzle. Add an LDC it is just silly quiet.

Motorhead,
May I ask what gun you are referring to? Thanks. S7

 

[Motorhead]

Motorhead,
May I ask what gun you are referring to? Thanks. S7

That would be my custom built Bottled marauder that utilizes a Balanced valve, Light hammer with adjustable lift, SSG spring control and then very finely tuned/adjusted.
The original build is here: https://www.gatewaytoairguns.org/GTA/index.php?topic=169004.msg155898655#msg155898655
As trials went along in differing calibers, it now sits as a .30 utilizing a 700mm FX SH liner in tension.
Bit of .30 info here: https://www.airgunnation.com/thread...2cal-to-30cal-conversion.1286404/post-1453042

The JSAR Raptor was a huge inspiration & became the base in further refining the tech and air control/management utilized in this one off build.

 

[Regaj]

@Regaj Why is .30 the obvious choice for that discipline

Sorry for the delay in getting back to you @18.13 - have been away on a motorcycle trip.

I can think of two reasons why .30 caliber dominates 100-yard airgun Benchrest... the first is the ballistics of a .30 pellet as opposed to a smaller pellet. The larger, heavier .30 cal pellet will be less affected by wind. And so even with comparably accurate tunes, the larger caliber has an advantage.

The second, and equally as telling, advantage that .30 cal has over .22... is the larger hole on target. A .30-size hole will pick up an 'X' where a .22-size hole might not. In centerfire score Benchrest the .30 BR rules for just that reason.

All that said, a .22 can win... as demonstrated by last year's RMAC.

 

[Sanctify7]

That would be my custom built Bottled marauder that utilizes a Balanced valve, Light hammer with adjustable lift, SSG spring control and then very finely tuned/adjusted.
The original build is here: https://www.gatewaytoairguns.org/GTA/index.php?topic=169004.msg155898655#msg155898655
As trials went along in differing calibers, it now sits as a .30 utilizing a 700mm FX SH liner in tension.
Bit of .30 info here: https://www.airgunnation.com/thread...2cal-to-30cal-conversion.1286404/post-1453042

The JSAR Raptor was a huge inspiration & became the base in further refining the tech and air control/management utilized in this one off build.

I read what you posted in the links Thank you. S7

 

[18.13]

Sorry for the delay in getting back to you @18.13 - have been away on a motorcycle trip.

I can think of two reasons why .30 caliber dominates 100-yard airgun Benchrest... the first is the ballistics of a .30 pellet as opposed to a smaller pellet. The larger, heavier .30 cal pellet will be less affected by wind. And so even with comparably accurate tunes, the larger caliber has an advantage.

The second, and equally as telling, advantage that .30 cal has over .22... is the larger hole on target. A .30-size hole will pick up an 'X' where a .22-size hole might not. In centerfire score Benchrest the .30 BR rules for just that reason.

All that said, a .22 can win... as demonstrated by last year's RMAC.

There are several .22 and .25 pellets with a better BC than .30 and shooting N50 they score with a .35 plug so not so much of a advantage

 

[Nattboy]

Thank you all for the education.

 

[Sanctify7]

Sanctify7,

Are you asking me to be succinct? That is somewhere between impossible and torture

There are a number of overlapping factors that predict which caliber would be quieter. The same factor does not always dominate. An attempt to oversimply with blanket statements of an absolute nature are not helpful.

As an introduction to the answer to your question; you do not need to drive a .30 as hard to make a given FPE as you do to get that from a .25 or .22. This is because the larger base area of the projectile delivers more force at a given air pressure - assuming you can flow enough air. "Driving hard" has to do with the percentage of maximum power that platform could deliver in that caliber, and with that projectile weight. Part of the equation is about how wide the flow area is, and how long the valve is wide open.

If you run any PCP close to its maximum power it will become louder. With a .30 you do not need to run it very hard to make significant power. But, if you run a .30 as hard as you need to run your typical .25 or .22, then the .30 will make much more power and more noise.

If your regulator setting or air tank pressure is low (1000 PSI or less), and you insist on making lots of power, then the only way to achieve that, is for the valve to stay open much longer. This will result in the muzzle pressure being higher, which will make more noise.

I think I am already repeating myself. I desperately want to draw charts of air pressure decay curves inside PCP barrels. Rather than do that, I suggest you read the threads below. They cover this topic clearly, with plenty of graphs; with calculated or measured data - rather than blanket statement about complex conditional interactions:

​

Maximizing power for a minimal noise level:​

Maximizing power for a minimal noise level - Airguns & Guns Forum

Maximizing power for a minimal noise level, Air guns, Airgun Forum

www.gatewaytoairguns.org

Acceleration and velocity of a pellet inside a PCP:

Acceleration and velocity of a pellet inside a PCP - internal ballistics - Airguns & Guns Forum

Acceleration and velocity of a pellet inside a PCP - internal ballistics, Air guns, Airgun Forum

www.gatewaytoairguns.org

EDIT: One more thing that is often not considered; the larger and heavier the projectile, and the more energy it carries, the more noise it makes when it hits the target - or whatever is behind the target. That could be a reason not to plink or pest with a .30 in urban areas. But, it makes sense for larger critters, or longer range shooting - assuming projectiles with a better BC than the smaller calibers. The latter is not a given: .22 slugs tend to have a higher BC than .30 pellets, for example.

Subscriber,

Thanks for the data, and I wish I could have gotten back to you sooner.
You have given me lots to think about (especially with those charts) and probably more than I can do something with. I may be in the majority with that last comment. But you did expand my horizons.

Here are a couple of things I think (?) I have learned. Do feel free to tell me if I am incorrect. I am not knowledgeable in this area, so it would not be a surprise to find out I am off base. Also, rather than go back and study the charts and isolate different ideas, I am presenting you with a collation or distillation of ideas, perhaps wrongly so. Please forgive me if that's the case.

One, and generally speaking, we cannot give simplistic answers to complex situations. I know that's true in my field, so I got it.

Two, you offered what I would call an ideal or unaffected model and then variously reevaluated that model according to real-world impingements, for example, barrel friction.

Three, the shorter time the valve remains open the better. Here, the projectile may be in, say, the middle of the barrel, and the valve closes and the air release is completed, but if the blast of air is sufficient it will still cause the projectile to travel at a sufficient speed; however, because the air release has ceased well before the projectile (pellet, slug) has exited the barrel, two objectives are achieved: there is a gain in air efficiency (shot count, and whatever else) and also less blast at the muzzle because excessive or unnecessary air is not following the projectile for its full travel and out the muzzle. (I don't know what is meant by a "square" air blast, if I remember correctly that this was the terminology used.)

Four, and moving to a different part of your comments, if a .30 were to be run lightly or at medium strength, give or take, it could achieve the same or better FPE than a .22 or .25 could if they were run hard, and produce less noise?? Besides my noise comment, this is merely a restatement of what you said, I hope.

Nothing brilliant is being said here, I know.

So, let me ask you a couple of things pointedly and perhaps somewhat redundantly.

One, all other things being somewhat equal, or even approximate, if a .30 Crown MkII were run to achieve between 50 and 70 FPE, how much louder would it be than a .25 in the same gun and barrel length that was achieving 40 or 45 FPE? To me, even rough comments would help. I own the .25 so I know what it is like, at least in the short 380mm barrel, to date.

Two, I am not sure I understand what regulator and hammer settings would be better or worse if quietness was the goal. I was under the impression that lower settings (reg, PW, and hammer) that produce less FPE equate to less noise. Is this one of those things that is not an absolute? Is it an absolute in the same gun with the same projectile?

If I am missing you, I hope it is not by a mile.
If you don't feel like answering everything, that's fine; anything you do say will likely help me.

Thanks for all!
S7

 

[subscriber]

S7,

Most of the muzzle report's sharpness comes from muzzle pressure. So, if you have a .30 and .25 using the same reg pressure setting, with similar report sharpness, I am going to flip the question to: What would the power of your .25 be, if the .30 was yielding 70 FPE?

Approximately (.25 x .25)/(.30 x .30) x 70 = 48 FPE
In other words, proportional to the expansion volume in each barrel.

The square wave had to do with the valve opening, not the report. It simply means that the valve opens fully very fast, dwells full open for a short period; then shuts very fast. This is not actually possible because the valve has mass and inertia. System that are closer to a square wave than a sine wave are available with solenoid driven valves. I believe that some Daystate PCP models use something like that.

I know that a higher reg pressure setting would seem that it should be louder than a low setting. This is true, if the tune used a heavy enough hammer strike to produce (closer to) the full FPE obtainable at the high and low reg settings, respectively. But, if you achieve the same FPE, then the higher reg setting is quieter than a low reg setting, because the valve would need to open less wide, and for a shorter duration to achieve that benchmark FPE.

This is because that smaller volume of higher pressure air expands all the way down the barrel to a lower pressure at the muzzle, it is more efficient. Meaning more energy in the projectile, and less waste pressure at the muzzle. So quieter. While that air expands all the way down the barrel, the bulk of energy transferred to the projectile would happen earlier, in the first third of the barrel perhaps. While a much lower reg pressure may do the bulk of the acceleration in the first two thirds of the barrel length.

Think of two bows: One has a high draw weight and a short draw length. The other has a low draw weight and a long draw length. It is possible to set them up to produce the same arrow velocity, with the same arrow. In the case of the "high draw weight" PCP (high reg pressure), while the bulk of the energy transfer to the projectile happens early, and you could cut off a large section of the barrel and lose very little, the extra barrel length remains in place. What happens in that extra barrel length is that the air pressure drops far enough to reduce the muzzle pressure. So, in effect acting as the blast chamber on a suppressor.

The lower reg pressure PCP needs more barrel length to match the high reg pressure for FPE. So there is less barrel length to act as a suppressor chamber.

Likewise, one may assume that in an unregulated PCP, shooting a string from max tank pressure to where the projectile energy has dropped off by perhaps 25%, would be loudest at highest tank pressure, and quietest at low pressure. The reverse is actually true because projectile energy comes from average pressure down the barrel, and noise come from muzzle pressure and the volume of air released by the valve. Power VS noise also correlates with efficiency, and a PCP is more efficient when the air pressure is higher, because the valve closes earlier to produce rated power. It is noisier at lower pressure, because the valve has to open further and stay open longer to produce rated power.

I rest my case.

 

[Sanctify7]

S7,

Most of the muzzle report's sharpness comes from muzzle pressure. So, if you have a .30 and .25 using the same reg pressure setting, with similar report sharpness, I am going to flip the question to: What would the power of your .25 be, if the .30 was yielding 70 FPE?

Approximately (.25 x .25)/(.30 x .30) x 70 = 48 FPE
In other words, proportional to the expansion volume in each barrel.

The square wave had to do with the valve opening, not the report. It simply means that the valve opens fully very fast, dwells full open for a short period; then shuts very fast. This is not actually possible because the valve has mass and inertia. System that are closer to a square wave than a sine wave are available with solenoid driven valves. I believe that some Daystate PCP models use something like that.

I know that a higher reg pressure setting would seem that it should be louder than a low setting. This is true, if the tune used a heavy enough hammer strike to produce (closer to) the full FPE obtainable at the high and low reg settings, respectively. But, if you achieve the same FPE, then the higher reg setting is quieter than a low reg setting, because the valve would need to open less wide, and for a shorter duration to achieve that benchmark FPE.

This is because that smaller volume of higher pressure air expands all the way down the barrel to a lower pressure at the muzzle, it is more efficient. Meaning more energy in the projectile, and less waste pressure at the muzzle. So quieter. While that air expands all the way down the barrel, the bulk of energy transferred to the projectile would happen earlier, in the first third of the barrel perhaps. While a much lower reg pressure may do the bulk of the acceleration in the first two thirds of the barrel length.

Think of two bows: One has a high draw weight and a short draw length. The other has a low draw weight and a long draw length. It is possible to set them up to produce the same arrow velocity, with the same arrow. In the case of the "high draw weight" PCP (high reg pressure), while the bulk of the energy transfer to the projectile happens early, and you could cut off a large section of the barrel and lose very little, the extra barrel length remains in place. What happens in that extra barrel length is that the air pressure drops far enough to reduce the muzzle pressure. So, in effect acting as the blast chamber on a suppressor.

The lower reg pressure PCP needs more barrel length to match the high reg pressure for FPE. So there is less barrel length to act as a suppressor chamber.

Likewise, one may assume that in an unregulated PCP, shooting a string from max tank pressure to where the projectile energy has dropped off by perhaps 25%, would be loudest at highest tank pressure, and quietest at low pressure. The reverse is actually true because projectile energy comes from average pressure down the barrel, and noise come from muzzle pressure and the volume of air released by the valve. Power VS noise also correlates with efficiency, and a PCP is more efficient when the air pressure is higher, because the valve closes earlier to produce rated power. It is noisier at lower pressure, because the valve has to open further and stay open longer to produce rated power.

I rest my case.

Subscriber,
You have made me rethink how all this works, and I am gaining clarity. I think I caught your clarification how the bulk of the energy transfer to the projectile from the sharper air release (higher pressure) happens earlier in the barrel and the rest of the barrel now acts as a shroud (first third of the barrel rather than, perhaps, the first two-thirds). I think I got the square wave idea. I am thinking of how a blowgun would work: all the air pressure is hitting the projectile ‘evenly’ and not on a sliding scale of impact. Perhaps I am incorrect.
I am looking forward to matching your .30 and .25 numbers and assessing the report.

One again, thanks for the valuable time.
You may not have heard the last of me. S7

 

[subscriber]

S7

Research "popgun" and "blowpipe" with regard to airguns. The material you will find from Cardew is more pertinent to spring piston airguns, but it will add to your understanding of the two extreme modes of operation.