Looks like the FAQ sections has what you need.  It states that they are, but if you are using belt feds to use MG line models.  

Is the octagon shape only for cosmetic reasons, or is there a performance advantage?

The FAQ section didn't answer a single one of my questions.

Supposedly it helps with the mirage effect cans have when they get hot and obscure the shooters view/line of sight when aiming.

I got my 762 OSS out of jail yesterday. First thoughts - I noticed the Cerakote job wasn't the best. As I took it down a bit, I found that the machining was nice in most areas, but there were some burrs that were not cleaned up. I'll take some pictures this evening. I also found that it didn't necessarily want to come apart very easily. The flash hider muzzle brake (fhmb) is the reflex part that comes over the barrel. On the end of that inner sleeve is the blast module. The outer tube screws down over the complete fhmb and this is the Back Pressure Regulator (bpr). From there, you add the sound reduction module (srm), tighten and time it, then tighten down the end cap. It sounds complex, and it is, a little.

There is definitely a lot of machining and threading that happens in here, and they all turn the same way.
When I unscrewed the upper srm from the bpr, there was no issue (good)
When I unscrewed the bpr from the barrel, the whole bpr came off (good)
I wasn't able to get the fhmb to unscrew from the inside of the bpr very easily. I had to put it on another barrel, hold the fhmb tip that peeks out of the front, then turn the bpr outer sleeve - almost needs 3 hands (bad)
I got it, but the sharper angles will definitely take a toll on your hands if you;re not careful. I used a shop rag, but a tool would help here (bad)
I got the outer sleeve off leaving the fhmb exposed. My attempts to unscrew this from the barrel resulted in the actual blast module unscrewing first. (bad)
That left the very base of the fhmb module on the barrel. If it's under a rail, that will be difficult to get to, so use a spanner wrench in the grooves and remove. (bad)

This will likely be a bear to get apart when it's caked with carbon. I'm hoping OSS Suppressors chimes in here but I'm considering the silicone oil treatment to ensure ease of use, takedown, and cleanability.

Tag for future reading

I own a first generation OSS in 762.  One of the reasons I bought it was the perceived modularity.   I could use it on my 762 semi rifles and then on my 556 full autos.   Well I can't buy the pieces to use what I have on 556.   I was lead to believe that was going to be the case.  My dealer has nothing to tell me and can't get in contact with OSS.   I'm hoping that by posting here I'll get an answer.    

So basically I shoot it very seldom.  

I have a Saker that I abuse.

Can't get ie AAC latches and ATF horseshit or can't get ie... AAC other parts? Haha

No.  Yes.

The pitch your sales guy gave me at a demo was that cans issued to SF teams were blowing apart in firefights more often than not and that the designers were trying to make a can that wouldn't blow apart.

Same here. Luckily I did not pull the trigger and buy one. I could never get a straight answer.

Yea.   I bought it at full retail to boot.

Drunken NFA purchase or what? Nobody should pay full retail for any product

True.  I'm not buying things retail (I first look on the EE now).  Also I'm not going to buy anything that's generation one either.  

Ehh, proprietary gen 1 things, maybe

Ok, here are the pictures I mentioned earlier. Note, this is the 1275 (2.75" over the barrel) and not the 1425 (4.25" over the barrel). It was what was available at the time. Let me know if you have any questions and I'll try to answer them.
Here is the 300blk sbr I put it on. The upper is one of the 10.5 DSG uppers from the Black Friday 2014 sale.


Comparison to a 16" upper (LWRC with an MCSR rail)


Size comparison to a Specwar 762 on and off the rifle





Note the machining issues




Outer sleeve removed from the BPR leaving the FHMB - SRM already removed and placed aside


The end removed from the FHMB module


Spanner wrench needed to remove this part from the barrel.


The barrel threads after the eventual removal process.

The big question on everyone's mind, how does it sound compared to the SpecWar?

Damn! Talk about Friday afternoon deburr......

Ouch.  Although with the incredible amount of machining work to build these i can see where skipping final items like this is needed to cut down on labor/machine cost....to stay competitive.  

The damage to credibility happened when he said it, especially considering the content of the crowd hearing it.   Spending as much time pitching Fire clean as the suppressor didn't help.

Whats wrong with answering questions on this thread?

I think we are going to figure that out soon. Now that I have it in my possession, we can meet up and go test it. I should have the 556 1425 model at my dealer soon, so if we wait just a little, we can test all of them against all of the cans you have as well as the ones I'll bring along. Email coming later today.

I'll be honest, I thought I would get some acknowledgment from OSS on the machining or take down process.

If OSS wants to send me a free can I'll be glad to post detailed reviews ;)

So, OSS...any answers to my previous questions? Since you've come back to the thread multiple times now.

And I'd like to add a few more. From your website:



1. "At least 138 dB" and "as low as 138 dB" mean the exact same thing. Do you agree?
2. Do you really believe 138 dB is "well below hearing safe"?
3. I always see testing done to the left of the muzzle. Can you clarify this?

more port noise from the right side of a gas gun?

Sounds like the same guy.

I'm really on the fence about the $449 ones from Jake

Agreed, questioning OSS's statement that testing is done one meter to the right of the muzzle.

Thanks for the answers.

I would wholeheartedly disagree that 138 dB should ever be represented as hearing safe. OSHA guidelines state that employees shouldn't be exposed to sound levels above 140 dB. That's completely different than saying 138 dB is fine for your hearing. Hearing protection should still be worn at that sound level.

If you should still be wearing hearing protection, that's not hearing safe.

I think it's dangerous, erroneous, and misleading to claim 138 dB is "hearing safe."

ETA for the chart that's been posted here recently:



Claiming that something which you shouldn't be exposed to for even ONE SECOND is "safe" is like saying playing with liquid mercury with your bare hands is "safe."

I agree with everything you've said.  Unfortunately this isn't exclusive to OSS.  All the other manufacturers do the same thing and market anything <140 as "hearing safe."

Agreed. Just bringing it up with OSS here since this is the OSS thread. I looked around and only saw one other manufacturer who claims "hearing safe" for centerfire rifle silencers - I would assume there's more, but it doesn't appear to be common practice.

First double-tap.

The U.S. MIL-STD actually does not indicate left or right.

With regards to 1m to the side of the muzzle being "the standard", it may have now been long an industry standard, however:

5.4.5 Transducer locations

For shoulder-fired and hand held weapons, transducers shall be located at the center of each operator or crewmembers's probable head location. For other weapons the transducer shall be positioned 1.60 m above the ground surface; for sitting locations it shall be 80 cm above the seat. When the operator must be present, the measurement shall be made 15 cm from the rear closest to the noise source ( ie., muzzle or breech, as the case may be ) on a line between the operator's era and the noise source


This is followed by to additional placements:

5.4.5.1 Refence transducer

a. If required, a transducer shall be placed 200 cm to the side of the major noise source of the weapon ( e.g, perpendicular to the muzzle for closd breech systems and perpendiculr to the rear for rocket launchers) with the weapon and the sensor 160 cm above the ground.


b. If required, a reference transducer shall be located on the 135-degree or 225-degree radial ( taking the line-of-fire as 0 degrees ) For weapons of bore diameter greater than 20 mm, this transducer shall be located at a distance of 50 bore diameters measured from a point directly under the muzzle with a tube ( barrel ) elevation of 0 degrees at a height of 160 cm. For weapons of smaller bore diameter, the transducer shall be located at the same elevation as the muzzle at a distance of 100 cm.


So, in essence, the shooters ear is the primary measurement location, especially the ejection port side and the 1m to the side of the muzzle is a combo of the a. / b. from 5.4.5.1

According to what has been told to me by long time industry colleagues, the 1m to the side comes from the 70s, started by Reed Knight, Charles Finn and Down Walsh. The MIL-STD incorporated it as 2 m, however the 1m still exists as can be seen above.

There are some possible new standards coming out in the near future, it remains to be seen what is adopted on the MIL side and are there any new standards that will become commonplace for the civilian side test work.

We commonly measure 1 m to the side of the muzzle and at the shooters both ears ( especially on semi/select fire weapons )

This is how we portray it in our catalog:



We do measure from other locations as well, if customers specify something else.

Best Regards!

Tuukka Jokinen
Ase Utra sound suppressors

As I said before, here is a comparison to a few other cans. Same rifle, but with a Sandman S and an Omega.

Sandman S



Omega (note: the Omega is using the direct thread module, and not the ASR)

Thanks for posting this excellent information. If only every manufacturer was this transparent!

That would be a nice addition to the marketplace. I'm sure I could google it but do they have a parent company that operates here to make an easy transition?

I think the OSS design has merit, but is immature. They are already on Gen 5, and sweeping the previous ones under the rug. I think that if they survive, we will all be very impressed with them in another half decade, if innovation and problem solving continues.

Where is this?

To follow up, just to clarify that I was not intending to slight OSS or the posts by their staff.

They are rightly measuring at the shooters ear, although their numbers are from an enclosed space, whereas typically measurements are done in open areas to minimize the effect of the surroundings.

Main reason was to give some info, as there is a lot of "info" and opinions on the net on firearm sound pressure level measurements.

Regards!

Tuukka

Me of all people should have differentiated that.
I actually hit up Jake @ QRF about them and he says they're selling, enough that he wouldn't discount it further haha

So where can I get non registered stuff to use my 762 can on more rifles?   Such as 556 (1/2x28) mounts?

A microphone is a transducer as it converts sound pressure waves into an electrical signal. Obviously the choice of microphone is critical as the transducer needs to have the dynamic range to capture a gunshot as well as the response time and proper frequency response.



Yes, in this case, the medium is air.



Hertz is  cycles per second, which is in essence, frequency. Are you referring to sampling time domain analog signal? In which case the A/D converter that you use is important as it needs to have the resolution, bandwidth to properly capture the analog signal.



Depends. Do you have constructive or destructive interference happening?