Moderator Caliber Question

[rj.psenica]

I am contemplating purchasing a Yokozuna in .35 so that I can use it on a .35, .30, & .25

Can anyone with more technical knowledge and experience help me understand is this is a good or bad idea?

 

[Gerry52]

In my experience it's not a problem at all. I own ONE DFL Ronin,.30 cal. I use it on my .22, .25 and .30 with ZERO adverse effects & great sound moderation.

 

[woogie_man]

It won't be as effective as a dedicated unit for each caliber. Though I believe you can talk to Donny and get dedicated end caps for each caliber

 

[subscriber]

A counterpoint: Larger caliber PCPs generally produce more power, and are thus harder to make quiet. If you are happy with the sound of a .35 moderator on your .35 PCP, the smaller calibers will be quiet enough, because they produce less power, despite the reduced efficiency.

It will take a large moderator volume to quiet a large caliber. A larger volume than required for a small caliber. If you are using a large moderator on a small caliber PCP, it will be quiet enough, despite the reduced efficiency.

My only concern would be if the larger caliber moderator is long and heavy, to the point where it droops a skinny barrel, or upset the harmonics. Else, there is very little downside - providing you can tolerate the extra length and weight when doing whatever shooting you like to do. Avoiding extra length and weight is a good reason for using caliber specific moderators - but, only if it matters to you. Using one do-it-all moderator saves money.

 

[steve-l]

There are two primary factors that influence sound reduction. There are others as well but are actually quite minor. The first is volume and the second is moderator bore size. When it comes to volume, the larger the better. When it comes to bore size in my experience, .020" (.5 mm) diametral clearance around the pellet size is optimum. Tighter is not better. The down side is that to run that optimum clearance, the moderator must be in line with the barrel. Most commercial moderators use excessive bore clearance to avoid clipping complaints, as most moderators do NOT align perfectly to the barrel.

 

[mtnGhost]

It will take a large moderator volume to quiet a large caliber. A larger volume than required for a small caliber. If you are using a large moderator on a small caliber PCP, it will be quiet enough, despite the reduced efficiency.

Technically incorrect. It comes down entirely to the design, materials, and how they handle the gas pressures. There's some very tiny firearm suppressors on the market (e.g. from DeadAir) that can make pistols and rifles fly fart quiet.
There isn't much to the designs of these typical airgun moderators, so volume and exit bore diameter pretty much dictate performance. Longer barrels can obviously attenuate better than shorter barrels of the same diameter and materials, so it's often more difficult to quiet down shorter bores. I like the design of the Impulse moderators the best, but they'd be substantially more effective if they used proper materials for their baffle cones and spacers. Thin walled aluminum / chinesium generally keeps the Alphabet org away though.

My only concern would be if the larger caliber moderator is long and heavy, to the point where it droops a skinny barrel, or upset the harmonics. Else, there is very little downside - providing you can tolerate the extra length and weight when doing whatever shooting you like to do. Avoiding extra length and weight is a good reason for using caliber specific moderators - but, only if it matters to you. Using one do-it-all moderator saves money.

Fat heavy moderators really need to be properly supported by something along the lines of a stiff tensioned shroud to eliminate barrel droop (so long as the tensioned shroud doesn't screw up bore concentricity like most of them do. That barrel droop causes an arc in the bore, which is anything but good for the bore itself .. especially with the typical butter soft steel airgun barrels. The heavy cans on harmonic-ridden straw barrels like FX will usually give the shooter some positive - but temporary results, not realizing that each shot is contributing to uneven bore wear.

 

[subscriber]

mtnGhost,

PB moderators handle a smaller mass of hot gas that is at high pressure; that then contracts to a smaller volume as it cools. Airgun moderators handle a larger volume of gas at lower pressure (for the power they produce). Because airgun exhaust is cold, the thermal shrinking effect is not present. So, airguns need comparatively large moderators for their power. Thus, comparing airgun and PB moderators is technically incorrect.

There is also the matter of expected performance. PB moderators make injurious noises bearable. More potent airguns, or those with short barrels first need to be made hearing safe. At lower power for the caliber and barrel length, the focus shifts to reducing nuisance noise to the point that most people don't pay attention to it.

Do not fall for video of PB moderator comparisons. The sound level on video is clipped. Look at the values reported by the dB meters. 120 dB for a moderated PB is considered hearing safe, but it is as loud as a very loud un-moderated airgun. Show me moderated PB that have a report below 100 dB, that are not on .22 rimfires with long barrels. Mouse fart quiet airguns need their report below 80 dB. Going below 70 dB is very difficult and may be achieved by manipulating the measurement set-up, or using a "friendly meter".

At dB readings below 85, the nature of the sound is more important than the sound pressure level. Gun shots at night, off in the distance are not very loud, but clearly still sound like gun shots. Airguns need to sound like something else for backyard shooting.

Making an airgun moderator more effective for its volume, or smaller and lighter for a given effectiveness, has significant value. I have hundreds of designs exploring this, but AGN no longer allows publishing or discussing the details about how to make more effective airgun moderators.

 

[mtnGhost]

mtnGhost,

PB moderators handle a smaller mass of hot gas that is at high pressure; that then contracts to a smaller volume as it cools. Airgun moderators handle a larger volume of gas at lower pressure (for the power they produce). Because airgun exhaust is cold, the thermal shrinking effect is not present. So, airguns need comparatively large moderators for their power. Thus, comparing airgun and PB moderators is technically incorrect.

There is also the matter of expected performance. PB moderators make injurious noises bearable. More potent airguns, or those with short barrels first need to be made hearing safe. At lower power for the caliber and barrel length, the focus shifts to reducing nuisance noise to the point that most people don't pay attention to it.

Do not fall for video of PB moderator comparisons. The sound level on video is clipped. Look at the values reported by the dB meters. 120 dB for a moderated PB is considered hearing safe, but it is as loud as a very loud un-moderated airgun. Show me moderated PB that have a report below 100 dB, that are not on .22 rimfires with long barrels. Mouse fart quiet airguns need their report below 80 dB. Going below 70 dB is very difficult and may be achieved by manipulating the measurement set-up, or using a "friendly meter".

At dB readings below 85, the nature of the sound is more important than the sound pressure level. Gun shots at night, off in the distance are not very loud, but clearly still sound like gun shots. Airguns need to sound like something else for backyard shooting.

Making an airgun moderator more effective for its volume, or smaller and lighter for a given effectiveness, has significant value. I have hundreds of designs exploring this, but AGN no longer allows publishing or discussing the details about how to make more effective airgun moderators.

My point flew right over your head: the design is what's most important.

Let me guess, you're STO under a different handle?

 

[subscriber]

My point flew right over your head: the design is what's most important.

Let me guess, you're STO under a different handle?

I will take your STO remark as a compliment; but he is not me. You can see my design experimentation and progression on the GTA forum; specifically in the thread with the title Taming the bark of an Avenger. Those designs are very different from what STO uses, even though some of my latest designs incorporate Tesla Valves.

My point also flew over your head: If you already have a .30 moderator that works well enough on your .30 PCP, it should also work well enough on a .177. As a common example, stock Marauders use identical baffles for .177 through to .25. The bores are sized for .25, so they are "loose" for .177. Yet, no one complains that their .177 Marauder is louder than their .25. The reason being that smaller calibers generally produce less power than larger ones; so there is less air to handle.

The OP's question was not about what you would design for different calibers. The question was about an existing moderator in a larger caliber, being used on a smaller caliber. That implies the internals already exist; no matter how simple or sophisticated. Go and read my reply to the OP above again in that context. The one you deem technically incorrect.

What you said about "internals matter" is correct, but it did not answer the question asked. If you are asked if you prefer chicken or fish, answering "steak" may be true for you, but it is not answering the question asked. Why do I care? Because of your "technically incorrect" remark. If I left out detail in my original explanation, I am willing to go into as much detail as the forum will allow.

As for me being STO, I was tempted to ask if you were Stubbers under another alias

 

[steve-l]

mtnGhost,

PB moderators handle a smaller mass of hot gas that is at high pressure; that then contracts to a smaller volume as it cools. Airgun moderators handle a larger volume of gas at lower pressure (for the power they produce). Because airgun exhaust is cold, the thermal shrinking effect is not present. So, airguns need comparatively large moderators for their power. Thus, comparing airgun and PB moderators is technically incorrect.

There is also the matter of expected performance. PB moderators make injurious noises bearable. More potent airguns, or those with short barrels first need to be made hearing safe. At lower power for the caliber and barrel length, the focus shifts to reducing nuisance noise to the point that most people don't pay attention to it.

Do not fall for video of PB moderator comparisons. The sound level on video is clipped. Look at the values reported by the dB meters. 120 dB for a moderated PB is considered hearing safe, but it is as loud as a very loud un-moderated airgun. Show me moderated PB that have a report below 100 dB, that are not on .22 rimfires with long barrels. Mouse fart quiet airguns need their report below 80 dB. Going below 70 dB is very difficult and may be achieved by manipulating the measurement set-up, or using a "friendly meter".

At dB readings below 85, the nature of the sound is more important than the sound pressure level. Gun shots at night, off in the distance are not very loud, but clearly still sound like gun shots. Airguns need to sound like something else for backyard shooting.

Making an airgun moderator more effective for its volume, or smaller and lighter for a given effectiveness, has significant value. I have hundreds of designs exploring this, but AGN no longer allows publishing or discussing the details about how to make more effective airgun moderators.

Subscriber is correct. I have been an air gun enthusiast my whole life. Air guns are short range and residential area friendly. I never go to a shooting range with an air gun. Their value is that can be used in an urban environment safely. In so doing, moderators are very much part and parcel to this hobby.. Anything that threatens use in an urban environment should be discouraged at all costs as urban use is the primary application.

That said, moderator design is very much an essential part of this hobby. It is not illegal. The owner of this forum has elected to prevent discussion of moderator design because he is the website owner and has every right to do that and instruct all his moderators to enforce his site rules. That however does not make it not an important area of interest and activity within this hobby. I think we all can read between the lines and determine the owner's reasons, His interests are his alone and not ours.

 

[Justaguy]

I am contemplating purchasing a Yokozuna in .35 so that I can use it on a .35, .30, & .25

Can anyone with more technical knowledge and experience help me understand is this is a good or bad idea?

My Tatsu is rated .25/.30. I use it on my .25 DRS. It isn't 'mouse fart' quiet but it does take a LOT of the bark out of the shot. It was certainly worth the $140.

 

[cavedweller]

It won't be as effective as a dedicated unit for each caliber. Though I believe you can talk to Donny and get dedicated end caps for each caliber

I bought 4 dedicated barrel QD adapters in .177 and use one .177 Donny Fl QD moderator. Beware of clipping potential if not perfectly installed or if moderator isn’t oversized one caliber.

 

[dizzums]

Generally it's not going to matter much but I can tell you a 35 needs a big moderator volume wise, it's more important than the hole on the end ..