In regard to sound measurement at 96 feet in front or 1ft in front and 1 to the side. It is possible for two silencers to have the same sound level at the shooters position and 1 be much quieter than the other as you get farther from the rifle. People who shoot at targets that shoot back seem to appreciate the way the Ops Inc silencers work. Maybe the civilian market will too.

   There is a standard military test for suppressors, it is used in the supprssor industry as well. I think it is Mil STD 14-7c or something like that. The microphone is supposed to 1 meter off the ground and 1 meter to the left of the end of the suppressor. There are only a few decibel meters that can accurately measure gunshot sound pressure. They are quite expensive and not available at Radio Shack. The type of weapon, ammo, humidity, temp, terrain if the can is wet or dry can all impact the numbers. Only a few people in the business actually test to this standard. Most numbers given are a best case scenario.
    Another factor is how the can sounds to your ears, I have seen and heard cans that metered well but sounded loud to the ears and I have seen the opposite happen. I have never heard the OPSinc but have heard good things about them from people who know about supprssors. I will probably buy 1. That way I can justify my OPS inc brake and collar on the end of my SPR.

Quoted: Are you sure they don't have the right to ask you to prove the item is at the address on the form (unless you are away with it) 24 / 7?

YES!

There's a lot of smoke being blown in this thread about sound measurement.  I'm weary as hell of re-explaining it, so maybe when PHD sees this he'll weigh in.

Carry on...

Quoted: Are you sure they don't have the right to ask you to prove the item is at the address on the form (unless you are away with it) 24 / 7?

I've read of people with post office boxes listed as their address on their Form 4's, although I have never personally witnessed it. Do you think that they keep their suppressors in their P.O. Box?

ScooterP is correct.

MIL-STD-1474D has specific requirements for metering equipment. The standard location for sound measurement is 1 meter to the left of the muzzle at 90 degrees to the bore axis and 1.6 meters above grass. This is the location that most  in the U.S. use.

Quoted: The best way to solve this is to organize a place to meet and shoot all the different can's available. to see for yourselfs what can's sound is the loudest and travels the furthest.

***While this is perhaps a best way to see what is the most pleasing to one particular person's ear, this is far from scientific, as everyone's hearing is damaged in different frequency ranges.  This is why older people sometimes like the MK9K suppressors over the Raptor suppressors, for instance - the MK9K is actually louder, but has a nice, pleasing low tone that appeals to those that have lost high end hearing over the years.

There is alot of controversy about the the correct way to measure db from a weapon, very few people know what their talking about.  Just getting off the phone with people who work closely with proving grounds on this subject  assured me we are not informed enough to discuss it knowledgeably.

***I don't see too much controversy over sound measurement - the majority of the industry uses  MIL-STD-1474D.  Those who don't, are usually called into question as to why not.  Measuring far in front of the muzzle doesn't measure the event very well, it measures bullet flight noise.  Which is why 50BMGs 'sound' so good measured that way...  I have talked with Phil at length over why he does what he does, and I respect his decision to meter the way he does, but he opens himself to a lot of "what the heck?" questions to people that are used to the standard.  Example: If five competing designs all do 28dB, and OPS says they do 40dB - geez, must be REALLLLLY better. Right? But, when the playing field is level, all with same ammo, same gun, same day/temp/atmospheric conditions on a LDL800B or B&K 2209 with correct weighting and correct microphone that is capable of catching the rise time (fast enough) to capture the gunshot event, the dB numbers get a lot closer.  Watch what I say here - I have a good deal of respect for OPS cans, and consider Phil a colleague, not a competitor - but if you are wanting to talk comparisons, there's only one way to do them, and that's to use the same scientific testing standards for everyone on the same level playing field.  We've had federal agencies out here at Gemtech doing competitive testing with many brands of suppressors, and the results are often suprising.
I wish I could post some of these results, but we are often under non-disclosure, or it would simply be tacky to do so.

As far as 'we are not being informed enough to discuss this knowledgably" - I've found that AR15.com members are some of the most excellent resources on the web for M16/AR15 family weapons in specific, and on firearm subjects in general, and some very much know their stuff on this topic and others.  I have certainly come to know many of the members and posters here and I will be the first to defer to some of their experience, knowledge, and scope of study.

There are also newbies who are looking for information and people that post erronous things, but there are some real deal people on these boards, which is why I've come to frequent them.

As far as the "great shoot out", it would be cool - agreed.  This happened once, at the Machine Gun News 1995 Anniversary Shoot, but it was a lessons-learned experience that needed some fixing...  It will probably never happen again in an unbiased, believable way, and even if it did, the losing manufacturers would claim that they measured a non-indicative sample, broken can, wrong ammo/platform, etc.

There's simply too much at stake these days to make it happen voluntarily.


Regards,

Kel

Excellent post, kel.  

If Ops Inc. suppressor is full auto capable (as it is), it must be quite heavy construction. How much does that thing weigh?

MN

Thanks for the back up M4 Madness. It has been a while since I have done any testing and had forgot the exact protocol. By using this standard there is common ground to base comparisons. Kel is right, it would be hard to get all the manufacturers together for an unbiased test. There is too much to lose. Listen to as many different cans as possible before buying, that way you can get what sounds good to you.

See their website link from 1st page of the thread.

Tag.

anybody know an approximate price on the ops ones?  the gemtech site has it out there for all to see, but i can't find $$$ amounts on the ops site.  also are the videos atleast somewhat accurate as far as sound reduction or has somebody messed with the audio(when editing video it is very easy to turn down the audio)?  it seems like you hear a lot more of the gun action than the round firing.  no disrespect is meant to ops but i am just curious.

Send Phil an e-mail for the cost of cans, they are very competitive prices.

I am the one in the video's (M-82 Video's are Ed Haywood shooting) and was with Mike while he put the site together, we absolutly did not mess with the audio in anyway.

You can do the same demonstrations and you will get the same results. Shooting the M-24 straight up in the air with and without the can was to show how quiet it is when there is nothing for the shock wave to echo off.

Quoted: anybody know an approximate price on the ops ones?  the gemtech site has it out there for all to see, but i can't find $$$ amounts on the ops site.  also are the videos atleast somewhat accurate as far as sound reduction or has somebody messed with the audio(when editing video it is very easy to turn down the audio)?  it seems like you hear a lot more of the gun action than the round firing.  no disrespect is meant to ops but i am just curious.

No, the videos are not accurate.  The recorders are not sensitive enough.

Just arange soemthing with Phil or one of his reps, do the same test thats on the video, you will be surprised how quiet it is with 2750 FPS ammunition, which is what were useing in those clips with the M-24.  

I can compare, from personal experience, the OPS can, a gemtech M4-96 and an AAC M4-2000.  To me, the OPS can was a bit quieter than the Gemtech, and I think it was about the same as the M4-2000.  Obviously this is just what I thought, but the cans are damn quiet.

Quoted: I can compare, from personal experience, the OPS can, a gemtech M4-96 and an AAC M4-2000.  To me, the OPS can was a bit quieter than the Gemtech, and I think it was about the same as the M4-2000.  Obviously this is just what I thought, but the cans are damn quiet.

When Al Paulson tested the Gemtech and AAC suppressors using Black Hills 62-grain ammunition on a 14.5" barrel:

Gemtech M4-96D -- 32 dB reduction.

AAC M4-2000 -- 33 dB reduction.

This should give you a general idea where the OPS can fits into the picture.

Quoted: 40 dB on several of the 5.56 cans... Oh wait here is the fine print: Measurements taken at 96 feet in front of the weapon. What a joke. The best way to solve this is to organize a place to meet and shoot all the different can's available. to see for yourselfs what can's sound is the loudest and travels the furthest. OPSINC cans are no joke, they were developed for use with full velocity ammunition and are the most  durable and accurate on the market, they are among the most quiet at the muzzle and there sound disapates more quickly then any other.  Some of the best Operators from each service from this country and others pay for these cans with their own money because they prefer them. The measurement  taken at 96 feet in front of the weapon was done to show the sound is 1/100  of what it was at the muzzle.  There is alot of controversy about the the correct way to measure db from a weapon, very few people know what their talking about.  Just getting off the phone with people who work closely with proving grounds on this subject  assured me we are not informed enough to discuss it knowledgeably.  If you want to argue the  mathamatic  dynamics of sound attenuation and the purpose for the types of equipment used in differentiating all the sounds that are actually occuring so true readings can be taken, we better get some very educated people  in on this topic. what is an approximage db for an ar15 223/5.56 without suppresion? M193 / 5.56  6' to the left of the muzzle is approximately 165db.

Sounds like a discussion to take to the tactical forums board.

regarding the tax stamp / atf form, is that for any item in a given amount of time or is it 1 tax stamp / atf form per item?

Walk a little North.....we'll hook you up.

Quoted: regarding the tax stamp / atf form, is that for any item in a given amount of time or is it 1 tax stamp / atf form per item?

Per NFA item.

Quoted: Quoted: Quoted: 40 dB on several of the 5.56 cans... Oh wait here is the fine print: Measurements taken at 96 feet in front of the weapon. What a joke. Well if I'm reading the site right it says 40 dB attenuation.  That, and if the reading is taken at 96 feet  it would mean it's 40 dB quieter from that far away.  Imagine how much quieter it would be from right next to it. ???????????? You're telling me "the closer I get to a gun, the quieter it is"  ?   THINK, McFly!

In relation to one another.  Obviously it's louder next to the gun... that's not the question I was asking.  I'm saying that if the readout is from 96 feet away and it drops 40 db then it would stand to reason that the the db drop next to the gun is more than 40 db.  

Quoted: Quoted: regarding the tax stamp / atf form, is that for any item in a given amount of time or is it 1 tax stamp / atf form per item? Per NFA item.

damn, the govt want their $$$$

Quoted: I'm saying that if the readout is from 96 feet away and it drops 40 db then it would stand to reason that the the db drop next to the gun is more than 40 db.

Why? It is going to sound quieter the farther away from the rifle you are. If you were a mile away, it would sound really, really quiet. The OPS can is not reducing over 40 dB using the standard SPL measurement.

The ospinc can was designed so the sound emited from it are high frequency, not low like all the other cans manufactured.
"The patented design of the devices raises the normally low frequency blast sound to a primary ultra high sound pitch"
 It's a In Phase / Out of Phase issue, high frequency disapates faster then low frequency that's why the audible sound is less closer to the shooter then any other cans.

Quoted: [ ***I don't see too much controversy over sound measurement - the majority of the industry uses  MIL-STD-1474D.  Those who don't, are usually called into question as to why not.

Why Not? Because trying to characterize sound reduction across 20-20K frequency range with a single dB number is just plain assine. And for some SPECOP applications, reduction ABOVE 20k is important too.

Example, most people over 10 years old cannot hear 19,500 Hz, but if the sound equipment detects -42 dB at that frequency, you all of a sudden you have a 42 dB can, even if it only reduces sound between 20-10K Hz by 10 dB, which is what most people can hear. So canmaker "A" touts their 42 dB can, even though it will appear to be one of the loudest on the market to most people.

At a minimum, the standard should be changed to report dB at 1k frequency intervals, and/or give a graph of this...

Quoted: Quoted: I'm saying that if the readout is from 96 feet away and it drops 40 db then it would stand to reason that the the db drop next to the gun is more than 40 db.  hr Why? he

Yes it is going to sound more quiet farther away, but  we are dealing with a ratio here.  

For example:

In an open area with no reverberation, the sound intensity from a point source will drop off according to the inverse square law:

http://hyperphysics.phy-astr.gsu.edu/hbase/acoustic/imgaco/isqb.gif

If the distance from the sound source is doubled, the intensity is down to one fourth, so

http://hyperphysics.phy-astr.gsu.edu/hbase/sound/imgsou/i3.gif

A doubling of distance from the source should give you a 6 dB drop if the inverse square law holds. (Note that decibels can be used to express any sound ratio in addition to the use for comparing to hearing threshold.) If the sound intensity in an auditorium followed the inverse square law, there would be a 20 decibel drop from the nearest listener to the most distant one if the nearest were at 10 ft and the most distant at 100 ft:

http://hyperphysics.phy-astr.gsu.edu/hbase/acoustic/imgaco/isqp2.gif

In any real environment - at least in any enclosed room - reverberant sound and background sound are always present and the inverse square law does not apply. If the intensity of the sound source is much greater than the background, then the sound near the source may approximate inverse square drop off- this region is often called the "direct sound field". At larger distances from the source in an acoustically "live" environment, the sound level may have little variation with distance because the room may be filled with the "reverberent sound field".

-----------
So what I'm saying is that if it's true there is a 40 decibal drop at 96 ft away then it's a greater decibal drop from 1 foot away (in relation to the original sound) because sound doesn't exactly gain volume as it travels (or intensity).

In an open area with no reverberation

This is why we shot the rifle straight up in the air 12 to 15 feet from the camera, with and with out the can on.
So the observer gets an idea of how quiet the can actally makes the discharge of the cartridge, without mistaking it with the sound of the supersonic bullet.

Quoted: www.atf.gov/dcof/index.htm This looks familar, and yes 24/ 7 they can knock on (not knock in) the door to make sure it is under the roof of that address with it's paperwork

Unless a former senior special agent of the BATF just lied to me 3 mins ago, when you sign a form 4, the address you put on that form can be visited 24 hours a day 7 days a week. They don't have the right to search the address but you are required to prove it is there along with the letter they returned to you for that particular serial numbered item.

Quoted: Unless a former senior special agent of the BATF just lied to me 3 mins ago, when you sign a form 4, the address you put on that form can be visited 24 hours a day 7 days a week. They don't have the right to search the address but you are required to prove it is there along with the letter they returned to you for that particular serial numbered item.

what if  you are on vacation and not present?  seriously... do they then take "stronger action"?

Quoted: Unless a former senior special agent of the BATF just lied to me 3 mins ago, when you sign a form 4, the address you put on that form can be visited 24 hours a day 7 days a week. They don't have the right to search the address but you are required to prove it is there along with the letter they returned to you for that particular serial numbered item.

You do not have to prove it is there, or even show it to him, that is in the BATF FAQ.  But you do need to be able to show your tax stamp should he ask to see it. Copies OK.

what if you are on vacation and not present? seriously... do they then take "stronger action"?

He said "he had never heard of anything like that"

Can you post the Faq links for me please, apperently word of mouth is not as accurate.

Quoted: what if you are on vacation and not present? seriously... do they then take "stronger action"? He said "he had never heard of anything like that" Can you post the Faq links for me please, apperently word of mouth is not as accurate.

You've posted more bullshit in this thread than I've ever seen spewed by one person in one place.  Please STFU until you actually know what you're talking about - you aren't impressing those who do know and you may fuck up a newbie if he listens to your silly shit.

Quoted: Can you post the Faq links for me please?

           NFA WEAPONS AND THE 4TH AMENDMENT

   As to surrendering your 4th amendment (search and seizure)
rights, this is definitely true when one gets a Federal Firearms
License.  The law allows the ATF to inspect your records and
inventory once every 12 months without any cause, and at any point
during the course of a bona fide criminal investigation (18 U.S.C.
sec. 923(g)).  They may inspect without warning during business
hours. The only modification of the above pertains to the C&R FFL
(type 03) where ATF must schedule the inspection, (C&R FFL holders
do not have business hours) and they must have the inspection at
their office nearest the C&R FFL holders premises, if the holder so
requests.  ATF may look around the licensed premises for other
weapons not on your records.  This means they take the position
that if your licensed premises are your home they may search it, as
part of the annual compliance inspection.  The constitutionality of
the warrantless "administrative search" of licensees provided for
in the Gun Control Act has been upheld by the US Supreme Court, see
U.S. v. Biswell, 406 U.S. 311 (1972).  Biswell was partially
overturned by Congress by 1986 changes to the requirements for a
warrant under the GCA, but the administrative search provisions
remain.

   In addition, if one is also a SOT, ATF claims to have the right
to enter onto your business premises, during business hours, to
verify compliance with the NFA.  Their regulation to that effect is
found at 27 CFR sec. 179.22.  The regulation is apparently based
upon 26 U.S.C. sec. 7606:

   7606. Entry of premises for examination of taxable objects.

   (a) Entry during day.

         The Secretary may enter, in the daytime, any building
   or place where any articles or objects subject to tax are
   made, produced, or kept, so far as it may be necessary for
   the purpose of examining said articles or objects.

   (b) Entry at night.

       When such premises are open at night, the Secretary may
   enter them while so open, in the performance of his official
   duties.

   (c) Penalties

       For penalty for refusal to permit entry or examination, see
   section 7342.

26 U.S.C. sec. 7342 provides for the penalty for a refusal to
permit entry under section 7606:

   7342. Penalty for refusal to permit entry or examination.

      Any owner of any building or place, or person having the
   agency or superintendence of the same, who refuses to admit
   any officer or employee of the Treasury Department acting
   under the authority of section 7606 (relating to entry of
   premises for examination of taxable articles) or refuses to
   permit him to examine such article or articles, shall, for
   every such refusal, forfeit $500.

   They claims this right extends to examining your business
records, and firearms.  This would only apply to your NFA firearms,
although they could presumably examine other guns to make sure they
were not NFA firearms, and subject to the law.  This is not subject
to the controls found in the GCA, noted above, as the legal basis
for the search is not found there.  So they could claim a right to
do this sort of search once a month, or once a week.  I am not
aware of any current abuse of the authority under this section.  
While the regulation made by ATF only applies this authority to
SOT's, the statute itself is not so limited.   At least one court
case has suggested this power is available to search an FFL holder
who is not an SOT.  (U.S. v. Palmer, 435 F.2d 653 (1st Cir. 1970)).

   As to one who is neither a FFL nor SOT, but only owns weapons
regulated under the National Firearms Act, ATF may only compel you
to show an agent upon request the registration paperwork, that is
the Form 1, 2, 3, 4, 5 or whatever else might have been used to
register the weapon.  See 26 U.S.C. sec. 5841(e).  They do not have
any right to compel you to produce the weapon.  As always the
Fourth amendment applies, and ATF may not enter your home or other
place of storage of the NFA weapon, nor seize the weapon, without
a warrant, or without falling under an exception the Supreme Court
has created to the operation of the Fourth amendment, or without
your consent.


www.titleii.com/BardwellOLD/nfa_faq.txt

You've posted more bullshit in this thread than I've ever seen spewed by one person in one place. Please STFU until you actually know what you're talking about - you aren't impressing those who do know and you may fuck up a newbie if he listens to your silly shit.

I posted one thing that i was told about the law by a former agent that works for a class 3 dealer and has an ffl. I was under the impression he would know. This isn't in the 114 page 2002 Federal Firearms regulation reference guide either and it isn't going to mess anyone up that files the form 4 anyway.

I'm not trying to impress anyone, the ones who do  know about these can's which are the topic of the thread, like you say "they do know".
-------------------------------------------------------------------------------------------------


Thanks for the link M4Madness.

The top of this link does state:

This is accurate, to the best of my knowledge, as of 12/30/2001. Nothing written here should be taken as legal advice.  If you have a specific legal problem, you should talk to a lawyer.

Quoted: You've posted more bullshit in this thread than I've ever seen spewed by one person in one place.

Yeah, I just read this thread from page 1 and it is hysterical. I will admit I was in error in not knowing there is a MIL-STD for sound testing - MIL-STD-1474D, I thought it was just a de-facto standard.

Is Ops Inc actually interested in selling these things or just posting pretty pictures on the web?

I emailed a price request four days ago and haven't received a reply (or auto reply).

If your time is too valuable for my simplistic request maybe you should post MSRP on the site to weed out tire kickers.

I don't work for them, i believe Phil is out of town at some deal at the moment, he's not answering the phone either. He often goes to bases when ever they ask and shows to demo cans.

He will get back to you.

I just spoke with him, he just got home and is replying now.

And i quote, "damn i am "80" and have been up for 32 with 2 hours sleep and haven't eaten".

You've posted more bullshit in this thread than I've ever seen spewed by one person in one place. Please STFU until you actually know what you're talking about - you aren't impressing those who do know and you may fuck up a newbie if he listens to your silly shit.

Read the last line on the actual Form 4 form this link. www.titleii.com/pdf/032804Form4.pdf

" This approved application is the registrant's proof of registration and it shall be made available to any ATF officer upon request."

Next question is "where is the item that this registration has approved". If you fail to provide it willingly they can obtain a search warrent (rather quickly) to search your home.

The rules aren't  bad for the state who's citizens can have them, just be nice if they come to look if it ever happends... which i am told very seldom does.

Back to the surpressors, how would one compare the .223 supressors on a M4 carbine to that of the Knights M4 supressor?  Ive heard the M4 supressor, sounds cool but the sound is still very distinguishable from 200m in the desert.  How would someone with good ears compare the two as far as sound reduction goes?  Oh ya, compare the prices too, let me know how much I save with the Ops Inc unit.

Quoted: Next question is "where is the item that this registration has approved". If you fail to provide it willingly they can obtain a search warrent (rather quickly) to search your home.

A BATF agent is really the only person who can compel you to provide a copy of your Form 4. No LEO can, although they could probably hold you until the BATF can confirm that you legally own the NFA item. It would be a big enough hassle that it would be better just to show anyone in law enforcement, although you legally do not have to.

As for the BATF making you produce the NFA item, I seriously doubt that they'd ever ask. I've heard of guys on this board owning NFA items for 30 years and NEVER getting a visit from the BATF. In fact, I know of no one who ever has. The BATF is restricted by the 4th Amendment, as it should be. They would have to have probable cause to believe that you've committed a crime in order to obtain a search warrant. Just wanting to know where your NFA item is located is not enough cause.

All you hear in the desert or anywhere for that matter at 200 meters is the shock wave of the bullet.  Which has the targets looking off in the wrong direction.  While you gain submission and compliance .

If you trust anyone to shoot at (near) you from whatever distance your curious about, you will get the idea, with a smily on your face, knowing you will have it on your rifle The sound seems like it's comming form somewhere else... because it is... the bullet.

These don't fail in the field, are half the cost of the cans you mentioned, and dont require disassembly, if you feel you need to clean it (which is not  nessesary.)  Some guys will thorw it in a bucket of whatever and put it back on when your ready.

Of course this is all just cheap talk until these things are ACTUALLY sold to non LEO and outside of Commifornia.

I have a very simple question which I've possed in email form to OPS but have not recieved and answer.  

1. Will OPS inc sell me their two port brake for my SPR necessary for the future addition of their SPR suppressor to my Mk 12 Mod 0 upper and if so, how much does that cost?

and a new second question:

2. What modifications would I need to make to my M4 upper to allow it to accept an OPS inc suppressor?  My M4 currently has the standard A2 birdcage flash suppressor.

The goal here is to have one suppressor for both weapons.

Regards,
Gary

Hey, they're neat, I'm sure.  Whether they're so much better than an M4-96D is another question.  I seriously doubt it.  I think what we have here is the Coors Syndrome in action.(I can't get it, so ipso facto it must be better - anyone remember people driving to Colorado to bring back cases of Coors?? )

Gemtech has a proven track record of OUTSTANDING customer service and their products are excellent and reasonably priced.  What more can you ask for?

Of course this is all just cheap talk until these things are ACTUALLY sold to non LEO and outside of Commifornia.

They can, they have already.

The first post of this thread was the thrid person to get one. He is an officer but his Station refused to buy it through them, so he purachased it as a civilian.

Will OPS inc sell me their two port brake for my SPR necessary for the future addition of their SPR suppressor to my Mk 12 Mod 0 upper and if so, how much does that cost?

 The Mk 12 Mod 0 Uses the Model 12 MBS, the brake comes with it, if you were going to have a carbine and SPR upper.. for use with that same can, yes they would sell you a second brake and collar.

They were around $ 750 for the Model 12 MBS (includes the brake and the can as a system) when we made the site.

We are waiting on prices so we can update the site opsinc.us/ with the currect prices.

2. What modifications would I need to make to my M4 upper to allow it to accept an OPS inc suppressor? My M4 currently has the standard A2 birdcage flash suppressor.

 The specifications are included with the can, to keep it short .. it will need to be turned down for a short distance so the sleve (collar) will fit.  (see currect pic's of SPR topics on this site) The collar needs to slide on the barrel and indicate on a sholder.

I believe discussing specifics about suppressed systems is not allowed on the forum for legal reasons. So i can't post those measurements, it is very little work.

I thought you just said you don't work for OPS?

I just helped make and update their web site,  i am in  the video clips. But i do not work for the company.