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Cleaner Running Suppressor Options for Semi-Autos

Henryrifle

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Mar 30, 2017
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I recently put together a 6mm ARC and am enjoying shooting it in different roles. I have harvested several deer with it this year, shot it out to 1000 yards on a 2 MOA steel target very successfully and, just to see what would happen, shot it at 1300 yards with a 27% hit rate on 1.5 MOA steel.

I shoot everything I can suppressed out of 'consideration' for my neighbors who hate the sound of gunfire--even in rural GA!

I am primarily a bolt gun guy, and, as such, attached my Ultra 9 to the 6 ARC. I built the rifle with and SA adjustable gas block and there is no issue with function and the noise suppression is great. I still wear hearing protection but, no complaints.

The issue I want to address is the extreme carbon buildup on the bolt, carrier, charging handle, upper, lower and fire control group within about 10 shots. I always get carbon on my hands and ears too as I remove the foam plugs often coming in looking like I was workin' in a coal mine.

This may all be academic at this point because this problem my not be worth a $1000 and an 18 month wait type of solution. I am not looking for the optimum in sound suppression and would be willing sacrifice some suppression of sound for a solution that ran clean. Perhaps this wold help with rifles that are more difficult to suppress like the LMT MWS308 too?

I have done some research but believe that the real world experience many of you have would be invaluable.

Thank you in advance for your thoughts,
Henryrifle
 
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Dead air sandman series are low back pressure cans and can help. But I’m gonna agree with theLBC and say get a piston driven system is you want them to run cleaner
 
I recently put together a 6mm ARC and am enjoying shooting it in different roles. I have harvested several deer with it this year, shot it out to 1000 yards on a 2 MOA steel target very successfully and, just to see what would happen, shot it at 1300 yards with a 27% hit rate on 1.5 MOA steel.

I shoot everything I can suppressed out of 'consideration' for my neighbors who hate the sound of gunfire--even in rural GA!

I am primarily a bolt gun guy, and, as such, attached my Ultra 9 to the 6 ARC. I built the rifle with and SA adjustable gas block and there is no issue with function and the noise suppression is great. I still wear hearing protection but, no complaints.

The issue I want to address is the extreme carbon buildup on the bolt, carrier, charging handle, upper, lower and fire control group within about 10 shots. I always get carbon on my hands and ears too as I remove the foam plugs often coming in looking like I was workin' in a coal mine.

This may all be academic at this point because this problem my not be worth a $1000 and an 18 month wait type of solution. I am not looking for the optimum in sound suppression and would be willing sacrifice some suppression of sound for a solution that ran clean. Perhaps this wold help with rifles that are more difficult to suppress like the LMT MWS308 too?

I have done some research but believe that the real world experience many of you have would be invaluable.

Thank you in advance for your thoughts,
Henryrifle

Did you adjust the gas down to the least amount that still functions reliably?
 
Yes. With the suppressor on, I close the gas port until the bolt either fails to lock open on the last round or fails to strip the next round out of the magazine. From there I open the gas port 1 or 2 detents until reliable autoloading and lock open occur. This generally gives a 2:30 to 3:30 ejection of spent brass out of the rifle.

This is not unique to this rifle or this suppressor. That doesn't mean that I'm not doing something wrong across all the ARs that I shoot suppressed.

Thank you,
Henryrifle
 
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Hand loads or factory ammo? If so what type?

I was getting a 24” 6ARC running for a friend of mine, and the Hornady white box (108gr ELD) was FILTHY stuff. Not sure what they’re using for a propellant but it was grimy and this was unsuppressed. I can only imagine with a can it would be way worse
 
Hand loads with LEVERevolution but, was also the same with CFE 223 and the first few powders I tried, Varget and H4895. From my experience this is a fact of life when running a semi-auto suppressed. It is no different in my 6.5 Creedmoor SR25 or .308 semi using two different brands of suppressors.

Henryrifle
 
Not sure if it helps or matters much, But i was told to use a PRI Gas buster charging handle on suppressed ARs, So i did, One on a AR10 260, and one on AR15 6.5 grendel, Both get pretty dirty brass, bolts ext, But no gas or black junk on my face or out side of the gun. Never ran with out one so i dont know if it dose anything really.....? H4350 in the 260, and 8208 powder in the Grendel. Elite Iron Can.
 
Gonna second the OSS, or Larue Tranquilo, as they're both designed for that specific reason. In the interim, this will help significantly...
 

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I have read through several threads here and in the archives, many of which became somewhat contentious. I want to avoid being a catalyst for that kind of discussion and, want to more clearly state the issue I'd like to understand more and, potentially, address.

With the rifle I am inquiring about, a 6mm ARC with a 21.75" barrel, rifle length gas system, SA adjustable gas block and TBAC Ultra 9 30 Cal suppressor, there is no gas-in-the-face issue at all. This particular rifle is using a Vltor BCM Gunfighter Mod 4 ambi charging handle. This is not one of the gas buster type charging handles. There are no function or rifle operation issues to report.

What I would like to understand and eliminate or reduce is the very significant amount of carbon that is being deposited in the upper and its components and the lower including the fire control group.

I believe I understand that the majority of that carbon is coming from the barrel because the bolt unlocks while there is higher than desired chamber pressure and anything I can do to delay that unlocking will reduce the amount of grime being blown out of the chamber into the upper/lower. Is that right?

If yes, and assuming that I have correctly set up my adjustable gas block then, should I try a heavier buffer and or spring which is a lot less expensive than a new suppressor? Does that mean the bolt might be held in battery slightly longer even though it is unlocked or does it mean that the carrier actually moves slower causing the bolt to remain locked longer?

Not sure this is a viable option but would moving the gas port further toward the muzzle impact the timing of the bolt's unlocking by a meaningful amount?

Thank you for the feedback so far...

Henryrifle
 
A lighter buffer and reduced power spring will allow you to turn the gas block down even more than it is now.

Less gas being sent to the BCG means less carbon being deposited. I know it works for me on one of my 6 ARC rifles.
 
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As Dino11 wrote above, lowering the energy in the reciprocating mass will allow you to restrict the gas block further... overall reducing total quantity of carbon in the system introduced through the gas tube.

As you (HenryRifle) wrote above, increasing the mass of the system will delay bolt unlock to reduce blowback fouling.

How you balance your increase weight and springs is shooter choice.

Increase in weight increases reciprocating energy.
Increase in spring tension increases reciprocating energy.
Both increase bolt unlock delay.
(Increasing reciprocating energy has it's own consequences.)

Some people enjoy the process of balancing the system (me), some people don't (people who hire me to do it for them).

A high flow suppressor like the current OSS will reduce back pressure, and minimize whatever increase in action-fouling-carbon the back pressure of the Ultra is creating by direct blowback into the action.

(Moving port closer to muzzle will delay bolt unlock also. Anecdotally, 18" +2 rifles ARC rifles are running at 100%.)

--

If I was in your position, and looking for quick fix, I'd keep the action wet.

If you are getting enough oil on your eye-pro to not be able to see, back off a little.

Obviously, this won't address the total carbon in the system, but it will keep a lot of the junk suspended in the lube. Field strip, wipe down BCG and upper, addback lube... back to it... without a huge time commitment to scraping accumulated carbon.

How you manage chamber fouling is on you... (I keep an eye on it with a bore scope, and clean as necessary).

I don't have any time on a 6 ARC... so I have no idea as to the specifics of keeping up with fouling on that round/powder/whatever.

(Edited to minimize incomplete thoughts.)
 
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My DeadAir cans definitely cause less dirt than my other cans.
 
As Dino11 wrote above, lowering the energy in the reciprocating mass will allow you to restrict the gas block further... overall reducing total quantity of carbon in the system introduced through the gas tube.

As you (HenryRifle) wrote above, increasing the mass of the system will delay bolt unlock to reduce blowback fouling.

How you balance your increase weight and springs is shooter choice.

Increase in weight increases reciprocating energy.
Increase in spring tension increases reciprocating energy.
Both increase bolt unlock delay.
(Increasing reciprocating energy has it's own consequences.)

Some people enjoy the process of balancing the system (me), some people don't (people who hire me to do it for them).

A high flow suppressor like the current OSS will reduce back pressure, and minimize whatever increase in action-fouling-carbon the back pressure of the Ultra is creating by direct blowback into the action.

(Moving port closer to muzzle will delay bolt unlock also. Anecdotally, 18" +2 rifles ARC rifles are running at 100%.)

--

If I was in your position, and looking for quick fix, I'd keep the action wet.

If you are getting enough oil on your eye-pro to not be able to see, back off a little.

Obviously, this won't address the total carbon in the system, but it will keep a lot of the junk suspended in the lube. Field strip, wipe down BCG and upper, addback lube... back to it... without a huge time commitment to scraping accumulated carbon.

How you manage chamber fouling is on you... (I keep an eye on it with a bore scope, and clean as necessary).

I don't have any time on a 6 ARC... so I have no idea as to the specifics of keeping up with fouling on that round/powder/whatever.

(Edited to minimize incomplete thoughts.)
Some achieve the delay by adding length to the gas tube by using a "pig tail" type tube. I've never played with that idea but some use it in certain instances with shorter barrels to achieve the same result, so I suppose it might work for this purpose as well.
 
As you've noted, the supressor design is playing a large part in the carbon in your action. The trade-off for the suppression level with the TBAC is the high back pressure. You've tamed it to some degree with the adjustable gas block, but I'm guessing you're still getting a lot down the barrel (which is harder to modulate). I'd play with increasing the buffer weight to delay unlock, but the best answer is to use a can that was designed for semi auto (Surefire or Knights come to mind).

I went from a Silencer Omega on my 5.56 guns to a Surefire RC2 and the difference has been night and day. My lower used to get noticable gritty build up in less than 100 rounds, now I can shoot hundreds of rounds and it barely looks dirty.
 
Some achieve the delay by adding length to the gas tube by using a "pig tail" type tube. I've never played with that idea but some use it in certain instances with shorter barrels to achieve the same result, so I suppose it might work for this purpose as well.
If I was given a choice to delay bolt opening, I'd tap into the barrel further away from the chamber over the pigtail strategy. Some guys swear by them...
 
Everything written above is correct. This is a constant balancing equation for multiple variables. I tend to take the simpler approach and use an incredibly low back pressure can. My solution was a SiCo hybrid 46. It keeps my gun clean(ish) but I sacrifice decibel reduction
 
I would think that a .30 cal can on a 6 mm would not have that much back pressure but I have no experience with that can. I have a Q Trash Panda in 30 cal to go on mine. I am waiting on cerakote currently so cannot comment on how it runs.

Barrel on mine is a 16 inch proof carbon fiber with rifle gas. Not saying that the Rifle gas is too short on your almost 22 inch barrel, but does seem like a lot more dwell than what Proof thought was needed, just as a data point. However, I do not know the gas port diameters in play either.

After reading some of these posts on 6mm ARC, I will be curious to see how mine runs. I am going to run a standard weight BCG with Carbine buffer and Tubb AR 15 Flat wire spring. SLR adjustable gas block.

I will say on 2 of my 5.56 suppressed guns that have JP SCS, I do feel like it cleaned up the fouling by putting Tungsten weights in the SCS system. Both of those guns have SLR gas blocks also. But the extra weight in the system was noticeable when shooting the gun.
 
As others have mentioned above, there really is no quick, economical solution to your issue at the moment. Its goes back to the whole right to tool for the right job concept. If a can was designed for absolute sound suppression its going to cause issues in gas guns as more pressure is introduced into the system. Lower back pressure cans make a compromise on sound suppression levels but allow have less of an impact on the operating system. while you may be able to tweak a few things here and there, but at the end of the day, its going to be difficult to get a high pressure can to do low pressure things

you may be able to try something like a gas buster, but even though I liked the one I used in the past, I would not considering it a gamer changer.

I has a similar issue with my MWS when i tried run it with a full size gemtech gmt-300wm on my 16 and 13.5 inch barrels, while i really like the can on my bolt gun and rifle length mws barrels, it was an awful choice for the shorter gas system. Way too much recoil and gas was being sent back into the system. I ended up getting a dead air can and zero issues. I am soo glad I picked up that can, instead of frustrating my self trying to run the wrong can on it.
 
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too late for a piston gun?
I have two piston guns (LWRCI REPR (6.5-CM) and Adams Arms (300-BLK) that deliver the same carbon buildup when shooting suppressed. A piston system does not solve this. It's just an unsolvable problem when shooting semi's suppressed. I've learned to just clean after each range visit.
 
I’ve done some testing with the new Sig SLX suppressors and they are impressive. They were specifically designed to reduce back pressure and run well with semi autos. My department chose this can to suppress our 10.5” AR’s. It will be on the market shortly and would be a good option. I prefer it to the OSS which I’ve also tested.
 
I’ve done some testing with the new Sig SLX suppressors and they are impressive. They were specifically designed to reduce back pressure and run well with semi autos. My department chose this can to suppress our 10.5” AR’s. It will be on the market shortly and would be a good option. I prefer it to the OSS which I’ve also tested.
Any issues with the OSS? They seem to be having a lot of sales on those,which some take to mean, there's some issue with them???
 
Any issues with the OSS? They seem to be having a lot of sales on those,which some take to mean, there's some issue with them???
My only experience with the OSS was just a few mags through a 10.5” 5.56 AR. I shot it both day and night but didn’t shoot enough to speak to its longevity or reliability. Compared to other suppressors tested it was quite loud (painful without ear pro) and threw quite a large fireball at night. In OSS’s defense it was the 556K can using M193 ammo which is known to be flashy. My opinion of that combo was that it didn’t do enough (sound and signature reduction) to make the purchase worth it.
 
My only experience with the OSS was just a few mags through a 10.5” 5.56 AR. I shot it both day and night but didn’t shoot enough to speak to its longevity or reliability. Compared to other suppressors tested it was quite loud (painful without ear pro) and threw quite a large fireball at night. In OSS’s defense it was the 556K can using M193 ammo which is known to be flashy. My opinion of that combo was that it didn’t do enough (sound and signature reduction) to make the purchase worth it.
That's what I was wondering about. Thanks
 
Try a Vihtavuori powder. This alone may nearly eliminate your carbon fouling issues.

They burn cleaner than anything by a country mile, and are consistently among the most accurate powders money can buy. But they're pricey.
 
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@BuildingConceptsllc: Thank you for bringing up the Sig SLX. That was not on my radar and while it doesn't yet seem to be available for sale that could be an interesting option.

@Odysseus1911: I use Vihtavuori powders in a few rifles and do find it (N150) accurate and able to consistently produce low SDs, I am not sure there is an equivalent to LEVERevolution--maybe N540... Thanks for the suggestion.

Henryrifle
 
@BuildingConceptsllc: Thank you for bringing up the Sig SLX. That was not on my radar and while it doesn't yet seem to be available for sale that could be an interesting option.

@Odysseus1911: I use Vihtavuori powders in a few rifles and do find it (N150) accurate and able to consistently produce low SDs, I am not sure there is an equivalent to LEVERevolution--maybe N540... Thanks for the suggestion.

Henryrifle
Gleaning from the Vihtavuori site on similar cartridges, N135, N140, N150, N530, and N550 should also work in 6 ARC, depending on bullet selection.
 
@snarkscarbine: Standard carbine spring and a Kyntec buffer. Swapped in the standard carbine buffer but made no difference.

@Odysseus1911: Will be very hard to leave LEVERevolution. Amazing velocity, single digit SD and reasonable pressure. I use the 108 ELD-Match projectile.

As a bolt gunner, I wasn't even aware that there were lower back pressure suppressors. Want to get an idea of when we'll see the SLX available for purchase. I may know someone that can get an early one to try out. I'd be happy to try out an OSS too but that is less likely...

Henryrifle
 
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@snarkscarbine: Standard carbine spring and a Kyntec buffer. Swapped in the standard carbine buffer but made no difference.

I'd swap the Kyntec back in and get a different spring. For reference, In my Grendel I've got an H3 (5.x oz) and a Tubb Carbine spring. I really can't recommend the Tubb springs highly enough. With something higher octane like Grendel/6.8/ARC you're definitely going to want adjustable gas, heavy buffer, and stouter spring. TBH most 223 ARs run much better with a better spring and H1/H2 buffer, too.
 
All suppressors except for OSS and Larue Tranquilo are going to cake your gun with carbon. Physics. Even piston guns get caked. I run Surefire SOCOM cans that are supposed to be low-backpressure cans, and I guess they're better at that than other baffle cans, but flowthrough cans are going to be better for a "can-agnostic" experience. There is always a compromise, however. Flowthrough cans will always be louder at the muzzle than baffle cans, and baffle cans will make your gun run dirty, but are quieter. The quieter the can, the worse the function due to backpressure and carbon buildup.
 
The real answer here is the CGS Helios QD with vent end cap. Blows the rest out of the water, very low back pressure, no flash, pretty good sound reduction. Just a bit heavy.
 
I have two piston guns (LWRCI REPR (6.5-CM) and Adams Arms (300-BLK) that deliver the same carbon buildup when shooting suppressed. A piston system does not solve this. It's just an unsolvable problem when shooting semi's suppressed. I've learned to just clean after each range visit.

This is the most accurate response in the whole thread.

The key detail to understand is that almost all the fouling you’re dealing with comes back through the bore after the bolt opens, not through the gas tube. A piston system doesn’t help much with that; the only ways to really make a difference are to delay unlocking or to reduce back pressure in the suppressor.

To delay unlocking, I suggest trying an H3 buffer and then re-tune the gas system accordingly. Going to a light buffer and spring is the wrong direction for this purpose, because as said, the fouling is coming through the bore, not the gas tube. The heavy buffer has been a better solution in my experience although I usually don’t worry about it and stick with standard weights; just keep everything well lubed because running it dry in this condition will cause issues.
I also suggest that if you’re seeing 2:30 ejection, you’ve probably got it unlocking a little earlier than necessary.

Another option might be that LWRC (?) bolt carrier with the elongated cam pin slot, but I forget the name of it and haven’t tried one personally.

At the end of the day though you should still expect dirty cases and more fouling when shooting a semi-auto with a suppressor whether it’s a Glock or an AR or whatever; it’s just the nature of back pressure and fast bolt opening.
 
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The real answer here is the CGS Helios QD with vent end cap. Blows the rest out of the water, very low back pressure, no flash, pretty good sound reduction. Just a bit heavy.

This.
the only downside to the CGS Helios is price but as an S sized gas gun can it is the best on the market.

it has two endcaps one of which is vented to reduce backpressure and one that is solid to facilitate better suppression and both endcaps
work great at their intended purpose due to the unique design of the suppressors internals ( watch some videos on it its pretty crazy.)
the Helios actually has BETTER sound suppression than other 6.5"ish cans like the Omega 300 7" and Sandman S 6.8" according to PewScience.

another cool thing is that the Helios was designed for 5.56 rifles but due to the way their suppressors work they are naturally overbored and you can use it with anything up to 300 Norma Mag.
 
This.
the only downside to the CGS Helios is price but as an S sized gas gun can it is the best on the market.

it has two endcaps one of which is vented to reduce backpressure and one that is solid to facilitate better suppression and both endcaps
work great at their intended purpose due to the unique design of the suppressors internals ( watch some videos on it its pretty crazy.)
the Helios actually has BETTER sound suppression than other 6.5"ish cans like the Omega 300 7" and Sandman S 6.8" according to PewScience.

another cool thing is that the Helios was designed for 5.56 rifles but due to the way their suppressors work they are naturally overbored and you can use it with anything up to 300 Norma Mag.
I don't get how an end-cap difference keeps carbon back-pressure from returning to the BCG. If anything, it seems it would increase the gasses hanging out in the suppressor and back-pressuring to the barrel. What am I missing here?
 
I don't get how an end-cap difference keeps carbon back-pressure from returning to the BCG. If anything, it seems it would increase the gasses hanging out in the suppressor and back-pressuring to the barrel. What am I missing here?

the vented front cap turns it into an extremely low back pressure can like the OSS.
the Sealed endcap boosts suppression and makes it a remarkably quiet suppressor for the length.

basically the best of both worlds and it all comes from not the front cap on its own but the voodoo magic they put into the 3D printed design of the suppressor.

Alabama Arsenal Explains it very well in his video.
He starts talking about the baffle design @ 9:45



Here is a chart comparing the Helios in the Solid (S) config and the Vented (V) config from Pewscience's free public article.

back_pressure_suppression_plot_6.13_wm.png
 
It's important to note that the back pressure thing doesn't equal gas to the face and is specific host configuration dependent. According to PewScience data the only thing that has beat a Helios QD so far in sound reduction was a TBAC Ultra 9, and that was only by 1.6 points. This dude put up a simple chart of what's been tested so far using the overall PewScience Suppression Rating: https://www.instagram.com/p/CKTxvICrTSq/

You could also note that the Hyperion K (solid front cap) has even less back pressure on the PewScience chart than a Rugged Radiant in short config (which has 2 baffles) and also less than a vented Helios QD. The sole thing that matches the Hyperion K (solid) backpressure is a Dead Air Sandman K and the Hyperion K beats it in sound reduction by a whole 13.1 points. Hyperion K also beats the Rugged Radiant (short) by 17.0 points. And the Hyperion K can still accept a vented front cap. Hyperion K would beat an Omega in sound reduction too, but the Omega has an overly tight bore and ours is slightly larger than normal. An Omega only beats it in sound by 1.0 point, but the Hyperion K has .63 less backpressure than an Omega on a 1.00 scale, with the Hyperion K at .15 and he Omega and .78 (less being less backpressure).

We're able to beat many fullsize silencers with our much shorter silencer even with a slightly larger than normal bore diameter because of the unique internal design.

The Helios QD with the front caps we're releasing in the coming months make the silencer even more adjustable by the end user across the whole spectrum of sound, flash, and gas reduction. We'll also be releasing a titanium Helios QD which is like 11.5oz or something.

CGS titanium rifle silencers are stronger than other companies titanium rifle silencers for a few reasons. The design itself controls pressure regions and vents the first highest chamber pressure immediately and reintroduces it later. Heat and pressure are what kill a silencer and the Hyperion Tech controls that to make it a stronger system overall and prevents hot spots from forming. The manufacturing process gives it a more uniform grain structure compared to billet materials and it doesn’t have any points of failure like welds that can go wrong if done improperly so there's no worries about QC and such. We also use a proprietary heat treatment which makes it even stronger than other companies titanium silencers. The Hyperion Tech system is also capable of filtering particulates which limits baffle erosion significantly even when it’s over 800°F. Even after 12,800rds of Nexus 139gr Scenario L 260 Remington fired through an uncoated Hyperion on an 18” semi auto host in a very short amount of time as a torture test, the blast baffle had zero erosion despite being only ~.700” in front of the bare muzzle. All CGS rifle silencers since 2019 are internally coated with S Line which is a proprietary hexagonal boron nitride coating that prevents fouling from sticking in the first place so cleaning is largely a nonissue. But should the need ever arise the silencer can still be cleaned. The internal coating also helps limit/prevent titanium white sparking depending on the host.

The default front caps that comes in the Helios QD kit have miniature flash hiders built in which are already pretty effective despite their small size. We'll also eventually offer vented front caps which will have flash hiders for each peripheral vent as well. To see info on the effectiveness of the front caps that comes in the kit by default take a look at around 5:20 in this video: and look at it on a 5.5" 7.62x39: https://www.instagram.com/p/B5F9P1mgxUe/ and https://www.instagram.com/p/B5HAuDagxAU/
 
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You could also note that the Hyperion K (solid front cap) has even less back pressure on the PewScience chart than a Rugged Radiant in short config (which has 2 baffles) and also less than a vented Helios QD. The sole thing that matches the Hyperion K (solid) backpressure is a Dead Air Sandman K and the Hyperion K beats it in sound reduction by a whole 13.1 points. Hyperion K also beats the Rugged Radiant (short) by 17.0 points. And the Hyperion K can still accept a vented front cap. Hyperion K would beat an Omega in sound reduction too, but the Omega has an overly tight bore and ours is slightly larger than normal. An Omega only beats it in sound by 1.0 point, but the Hyperion K has .63 less backpressure than an Omega on a 1.00 scale, with the Hyperion K at .15 and he Omega and .78 (less being less backpressure).

We're able to beat many fullsize silencers with our much shorter silencer even with a slightly larger than normal bore diameter because of the unique internal design.

The Helios QD with the front caps we're releasing in the coming months make the silencer even more adjustable by the end user across the whole spectrum of sound, flash, and gas reduction. We'll also be releasing a titanium Helios QD which is like 11.5oz or something.

Ooooh that Helios QD Ti has my wallet cowering already super excited for that and the additional endcaps.

two questions for you since you seem to be from CGS.

1. from the design standpoint why does the Helios have higher backpressure and lower suppression in the vented configuration than the Hyperion K? obviouisly everything is a tradeoff and i was interested in what that give and take was considering the Helios was designed for Semi autos and lefties.

2. any plans on a smaller 4" or 5" Helios?
 
Ooooh that Helios QD Ti has my wallet cowering already super excited for that and the additional endcaps.

two questions for you since you seem to be from CGS.

1. from the design standpoint why does the Helios have higher backpressure and lower suppression in the vented configuration than the Hyperion K? obviouisly everything is a tradeoff and i was interested in what that give and take was considering the Helios was designed for Semi autos and lefties.

2. any plans on a smaller 4" or 5" Helios?

1) That's not info I can share. But being over bored for 5.56 has a bit to do with it.

2) Nothing I can comment on there either.
 
Just wanted to thank you all for the thoughts, ideas and data provided here in this thread. I started the process today with an OSS HX-QD 762 and look forward to comparing it to my current Ultra 9. I know it will louder--maybe much louder but I would willingly trade some sound for reduced blowback.

I don't know that I've made the best decision given all the options above but, I am looking forward to experiencing the difference and while I won't be able to compare it to other flow through cans, I will be able to determine the differences between it and my current solution. Will be back (in about a year?) for a subjective comparison.

Thank you all again,
Henryrifle
 
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......To delay unlocking, I suggest trying an H3 buffer and then re-tune the gas system accordingly. Going to a light buffer and spring is the wrong direction for this purpose, because as said, the fouling is coming through the bore, not the gas tube. The heavy buffer has been a better solution in my experience although I usually don’t worry about it and stick with standard weights; just keep everything well lubed because running it dry in this condition will cause issues.
I also suggest that if you’re seeing 2:30 ejection, you’ve probably got it unlocking a little earlier than necessary.......
My first thoughts also that a 2:30 ejection was a tad on the early opening/ gassy side. While you wait for your OSS it may not be a bad idea to increase buffer and spring rate and get your ejection at the 3:30-4:00 position to see how much that helps
 
Picked up OSS suppressor on Monday, 346 days after filing. Looking forward to testing it and reporting feedback soon!

Henryrifle
 
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I took advantage of sale price on an OSS HX-QD556k a few months ago, and then got busy with fall harvest & etc. before finally amending my trust and getting a copy of it to my SOT - waited so long that he was able to use ATF's eForm process. We'll see if that results in getting the stamp back any faster than before, as I'm still waiting on the stamp for an Gen 2 Ultra 7 that was filed back in late Feb 2021. After what I've read in this thread, I'm not expecting great things out of the OSS, but then again, I'd totally stopped using suppressors on any of my gas guns because of the mess. I've got a SF SOCOM762RC that I've used a little on Aero M5 in 6.5CM & 7.62, but never tried it on an AR15 in 5.56, even though I've got a 5.56 mount/brake for it. Aside from the novelty of shooting a gas gun suppressed, I'm thinking the price paid for gunking up the guts of a rifle and downgrading accuracy by hanging the mass of such a can off the muzzle are simply not worth it. Maybe the OSS can will modify my opinion...
 
Got a chance to shoot with the OSS today. I had already shot several groups with a bolt gun and admitting that I am not the best AR trigger puller may have even been a little worse than usual due to the differences between a competition rifle and my 6mm ARC AR. I was also using year old hand loaded ammo. There is usually no problem with that but you never know. I shot using a Harris bipod but did use my prone rear bag rather than my normal squeeze bag for rear support.

This rifle normally shoots in the .6 to .7 MOA range at 100 and today was about the same. I didn't think I pulled that last low shot on target 2. Both groups are a little out of tune possibly necessitating a small powder change. I took slow motion video of the rifle and didn't see anything unusual or smell/feel abnormal blowback as with the TBAC Ultra 9. I didn't take my ear plugs out though I intended to do so. To few shots to determine if the bolt is going to run cleaner but early indications are that the OSS can is a big improvement. No issues with bolt cycling or last round hold open.

I've missed hunting season with this rifle this year and will have to wait until next year to get serious with it again but hope to have a little fun with it this spring/summer shooting steel at distance.

At this point, I only have good things to say about the OSS can. No more gas in my face, good recoil mitigation and sounded fine. Will post more about carbon in the action when I know more.

Thank you all!
Henryrifle

Target from today below...

1-24-22 6mm ARC OSS can.jpg
 
Sounds good - gives me reason to look forward to getting the stamp for my OSS. I should order in a SLR adjustable gas tap or two so I'll at least be ready to try it when the stamp does finally come in.
 
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OP, I’d be curious to see a side by side of your cases with your OSS. Here is a side by side of .308 cases with and without an Omega 300. The camera makes the left look cleaner than it is.

595B4A0C-C6F6-4A1C-97C7-AA3AA93EE2F0.jpeg