Thread: Suppressor effectiveness - Think about this!

Are you going to provide the guns and the ammo, knowing that there are about a dozen brands represented on the NZ market and some with two or three models for one brand ? As to the muzzle brake, some require indexing to properly work...another little head hack .
Who is supplying the proper expensive testing equipment?

i can provide a .243, if you want to back your brand you will be there.
the guys doing the crazy car sound could do it again

Originally Posted by Friwi

As to the muzzle brake, some require indexing to properly work...another little head hack .

Some manufactures with some threads have DIY, self install brakes which means indexing is a breeze

I think we are missing a key point or two. And its again comparing apples with oranges if we focus purely on sound reduction.

Most customers in NZ are buying a suppressor that is a compromise, a balance between weight, sound suppression and cost.
Whether this is for hunting the hills with a bolt action or shooting a semi, usually for more rapid fire usage, ie targets or pest control.
I used to have two Reflex T8 cans, awesome 1990s technology designed for full auto use in the military.
Those things will never fail, could handle extreme rates of fire and temperature and were pretty good for sound reduction even compared to modern designs.
Would I use them for lugging around the hills in NZ again? No ffffing way!
I changed and went for DPT modular for my hunting rifles. For that purpose their light weight, low cost and pretty good sound reduction is hard to beat.
Even if they don't have the longevity of steel designs (although the new steel baffle insert is the solution in my opinion).

For a semi auto application, I would look elsewhere, for moderate cost and excellent sound reduction, but heavy weight is something like a ASE.
There are cheaper options as well, but again they aren't light. You would need that high spec testing equipment to separate these out.
There are also other design factors, such as internal muzzle brake and back gas design, again these things will costs more.
If you have the $ and want the best of everything, then you could go titanium, with ODL.

So testing purely on sound reduction is a bit pointless in my mind, as you need to give equal weighting to cost, weight and intended usage.

And the LEM by MAe that came on my latest purchase weighs more than one of the alloy heads on my car. But I expect no one will ever hear the gun go off or hope so cos you won't carry it too far that's for sure.

@6x47 the reference to the sound of a 747 at take off was a passing comment in @gonetropo explanation as wasn't even particularly relevant to his point.

Congraz on the super awesomely high level of condescendingness you achieved though.

Ricochet. (Storeman)

Originally Posted by dogmatix

I think we are missing a key point or two. And its again comparing apples with oranges if we focus purely on sound reduction.

Most customers in NZ are buying a suppressor that is a compromise, a balance between weight, sound suppression and cost.
Whether this is for hunting the hills with a bolt action or shooting a semi, usually for more rapid fire usage, ie targets or pest control.
I used to have two Reflex T8 cans, awesome 1990s technology designed for full auto use in the military.
Those things will never fail, could handle extreme rates of fire and temperature and were pretty good for sound reduction even compared to modern designs.
Would I use them for lugging around the hills in NZ again? No ffffing way!
I changed and went for DPT modular for my hunting rifles. For that purpose their light weight, low cost and pretty good sound reduction is hard to beat.
Even if they don't have the longevity of steel designs (although the new steel baffle insert is the solution in my opinion).

For a semi auto application, I would look elsewhere, for moderate cost and excellent sound reduction, but heavy weight is something like a ASE.
There are cheaper options as well, but again they aren't light. You would need that high spec testing equipment to separate these out.
There are also other design factors, such as internal muzzle brake and back gas design, again these things will costs more.
If you have the $ and want the best of everything, then you could go titanium, with ODL.

So testing purely on sound reduction is a bit pointless in my mind, as you need to give equal weighting to cost, weight and intended usage.

i can't see it pointless we just add the cost and everything else to the test and thereby we compare apples with apples , i guess we will never know then.

This isn't an unknown, there are tons of threads on here and on Fishnhunt doing backyard tests on suppressors with substandard sound equipment and even relying on old human ear drum Mk101, sorry Possumtrapper , as well as some good comparisons.

http://www.fishnhunt.co.nz/forum/YaB...1402472871/0#0

http://www.fishnhunt.co.nz/forum/YaB...1406260467/0#0

http://www.fishnhunt.co.nz/forum/YaB...1459450986/0#0

http://www.fishnhunt.co.nz/forum/YaB...1443598908/0#0

http://www.fishnhunt.co.nz/forum/YaB...1435475519/0#0

http://www.fishnhunt.co.nz/forum/YaB...1440616677/0#0

http://www.fishnhunt.co.nz/forum/YaB...1431327925/0#0

You can also check each manufacturer's website for their own testing results.

Without the very expensive equipment (most cheap stuff is only good for measuring continuous noise, not peak impulse noise) and a full range of equivalent suppressors (graded by cost, weight, material etc) in the same calibre and correct thread, its going to be hard to get a definitive answer.
Another key assessment should also be customer satisfaction, as there will always be some makers who go the extra mile and some who are lacking in customer services skills.

I previously mentioned that a suppressor thread on Fishnhunt ended up as a bitch and squabble between supporters and indeed suppressor makers, so I'll be pleasantly surprised if you can get the various NZ (and overseas - ASE are an active forum member) makers to want to be involved, as they won't want their products looking bad.

I do agree, having one set of testing under the same conditions would be good, so best of luck.

Originally Posted by Ricochet

@6x47 ..
Congraz on the super awesomely high level of condescendingness you achieved though.

Ricochet. (Storeman)

Thanks for that.
It's common to see someone offering technical advice when they clearly have "limited knowledge", but when they suggest people PM them for further info, that deserves comment.

Well 6x47, I for one would like a bit of input from an audiologist and I imagine most other would as well.

For more info than anyone would like to know about "doubling sound". This link will help. This goes into the necessary inputs of sound duration and other factors that contribute to subjective sound levels.

For a guide on higher level peak sound this PDF is very useful. NIOSH/Criteria for a Recommended Standard--Occupational Noise Exposure, 1998

I took the dBA dose percentage and calculated the number of shots each level would allow before breaking the "8 hour threshold". Shot impulses are in microseconds so even a small time fram seems to allow for several shots over 8 hours in a day at 140 or less.

I would like to get a professional view on whether this method is correct or even opinions on this, 6x47. The reality in hunting is that most people will not wear ear muffs and most will not shoot their rifle remotely from 450 meters. Subsequently some guide on the sound levels that are acceptable would be good. I know for a fact that suppressors can reduce sound at the ear better than some single ear protection setups with braked rifles.

Regarding recoil. Brakes inside a can cease being a brake once they are inside the can. I am producing my first Ratchet Locking can over a brake or flash hider now. When I was doing the first testing I asked the person shooting the 308 what they thought about the brake versus the can. Subjectively they said it wasn't much different. I am dead sure that the effect could be measured as the brake being better for recoil but like sound levels, there are other factors that make the rifle "seem" to recoil less. There is certainly less flinch inducing from a suppressor versus a brake.

More discussion on this topic will do the shooting community a lot of good.

The NIOSH doc is focussed on continuous noise. Noise dose modelling and its associated damage/risk criteria are relevant to this type of noise but not impulse noise. With the latter, you need to keep exposure to-any- impulse events under 140dBSPL (peak).

There is a somewhat separate (and much smaller) volume of literature on impulse noise. It is much more difficult to measure and requires far more expensive gear.

Yes the focus is on continuous but there is a specific section on impulse noise in 3.2 ceiling limit:

"The generally accepted ceiling limit of 140 dB peak SPL for impulsive noise is based on a report by Kryter et al. [1966]. Ward [1986] indicated that "this number was little more than a guess when it was first proposed." To date, a proposal for a different limit has not been supported. Henderson et al. [1991] indicated that the critical level for chinchillas is between 119 and 125 dB; and if a 20-dB adjustment is used to account for the difference in susceptibility between chinchillas and humans, the critical level extrapolated for humans would be between 139 and 145 dB. Based on the 85-dBA REL and the 3-dB exchange rate, the allowable exposure time at 140 dBA is less than 0.1 sec; thus, 140dBA is a reasonable ceiling limit for impulsive noise."

In the absence of any other data, this looks to be the only source that actually provides a guide for impulse noises between the 125 and 140 dBA ranges. Shooters will regularly experience levels in this range suppressed or with single layer of hearing protection for non magnum centerfire rifles. Braked and magnum shooters will exceed these limits with a single layer of hearing protection.

If there is more info available or better guides, I would like to see them.

Look the suppressors do reduce recoil , just not as much as a brake does , the only real research I can think of was done in Finland quite a few years ago , look that info up , they used I think a pendrulum device to measure the force , ie suppended from a pivot point etc .

Originally Posted by ODL

.. Based on the 85-dBA REL and the 3-dB exchange rate, [B]the allowable exposure time at 140 dBA is less than 0.1 sec; ..

In all the impulse literature I've read, I can't say I've seen detailed focus on time/energy integration. The tone of that sounds rather speculative.

Those refs quoted are very familiar to me- I did a Masters thesis on noise induced hearing loss in 1991 and most of the literature wasn't fresh even then.