Anyone experiment making high and low pressure in cans?

[John A.]

Maybe I should explain what I'm talking about. And since I've never seen this idea being used, is probably going to be tough for me to try to explain what I am thinking.

We know the sole duty of a suppressor and the relative theory in how they work.

What I am wondering about, is if anyone has ever experimented trying to make use of the pressure to have higher or lower pressures in a baffle, to perhaps direct the pressure to go a different direction other than forward and out of the can into the atmosphere, or away from the "normal flow" of the gas.

I believe the whole idea of porting or clipping in general is making use of directing pressure "flow".

But I was thinking about how one could perhaps direct more pressure back into a reflex portion of a can from within the expansion chamber, rather than just letting the natural expansion process move it back over the barrel.

*Especially since it's the highest pressure in a can, makes sense to use that pressure to do something, other than to simply exist as they do in most suppressor designs that I have ever seen. My whole idea is more directed, so it seems.

Here is a quick explanation to what's been rolling around in my head.

Use a ported muzzlebrake since they already port gas to the side rather than forward, and the expansion chamber be cone shaped so near where the bullet would exit from the brake, be narrow (should be a higher pressure because it is smaller diameter) and nearest the barrel, the larger portion of the cone, which should be a lower pressure because the expanding gas has more area, plus the whole volume of the reflex portion too.

Also, to explain something, the expansion chamber cone baffle would slide over the extreme front edge of the muzzlebrake and seat for a few reasons. 1. would be to help keep everything aligned, but mostly to seal off and block as much of the expansion chamber/ported gas from affecting the bullet path after it leaves that chamber.

I don't want a cone baffle directing the pressure onto the bullet affecting accuracy going into the next chamber, causing it to yaw or everything else, and why I was going to make the expansion cone butt up against the brake and essentially seal the expansion chamber from the rest of the baffles as much as I know how to.

I hope.

In my mind, the cone shape should direct some of the gas flow rearward and be more effective of filling the reflex portion. And thus, should also move a significant portion of the expanding gas away from leaving the suppressor and hopefully make the can more efficient and thus, quiet.

If there is another design like this out there, I am not aware of it. But I think it would work.

Whether it would be record-breaking or not; probably wouldn't be, but any improvement of efficiency is still an improvement nonetheless. I think we all have wanted to make the most quiet suppressor as possible by any means and this has been on my mind for years now. Along with a specifically shaped baffle that I am wanting to try along with this can.

If there is a similar design, I would be interested in learning more about it, and especially if I can find footage to hear what it sounds like.

So, here is a quick rough sketch of what I am trying to explain.



Hopefully between my vague explanation and rough sketch, may could get some opinions. Especially productive ones if there is some way to make it "better".

[fishman]

The pressure in the blast chamber is high, but not the highest. The pressure in the barrel is even higher. That's why a ported barrel integral is such good design but most people don't want an integral, and they don't want to port their barrels. If you are willing to do so, you're better off just porting the barrel into the reflex area and leaving the blast chamber sealed off from the reflex area. The cone and brake blast chamber could possibly be a good alternative if you AREN'T willing to port your barrel. I know one way to find out.

[John A.]

I don't mind to port the barrel.

Won't be the first one I've done and I would actually like to do that.

But my main reservation though, is it's a blackout, and I'm using a very fast burning powder that burns out within the first 6 inches or so of barrel to get it as quiet as I can to reduce blowback gassing, eliminate first round pop with the can I am using, and I have already had to use a reduced tubbs buffer spring and a taccom lightweight buffer and it has a .125" gas port just to get it to cycle reliably as it is already, so taking the pressure from the DI system is a concern because I am worried it may cause cycling issues and the last thing I want to do is use a slower burning powder because I've already worked up some really good loads and tuned the gas system so they'll work.

[bottomdweller]

i thought about doing something similar to relieve pressure only maybe too aggressive. What if a tube about the size of a gas tube on an ar maybe two, was placed 180 degrees apart running lengthwise with the outside tube going through each baffle into the back portion of the reflex chamber and out the front cap as far away from the bullet exit hole as possible. Seems like it would reverse direction of the gas for a little while making equalizing pressure throughout the entire length of the can.

[John A.]

I understand what you are talking about.

That would certainly be an "out of the box" design.

I could even picture something like a "pigtail" AR gas tube if you are trying to add distance from start to finish.

[a_canadian]

I'm completely inexperienced in this blackout thing, but your comments regarding this particular build make me wonder if it wouldn't be practical to both port the barrel for superior suppression with a significant amount of reflex volume, as well as moving the gas port block back to about 6". Wouldn't that make sense? You'd get your reliable cycling, while also dumping a lot of the burned gases out through the ports before even encountering baffles. Could make for a very quiet weapon... if it's not a completely nonsensical idea.

[bottomdweller]

Wow john, way cool. I'm gonna weld mine, so taking it apart isn't a big deal. Slowing while equalizing. Very cool. If heat a heat sink is beneficial that should work

[fishman]

I'm completely inexperienced in this blackout thing, but your comments regarding this particular build make me wonder if it wouldn't be practical to both port the barrel for superior suppression with a significant amount of reflex volume, as well as moving the gas port block back to about 6". Wouldn't that make sense? You'd get your reliable cycling, while also dumping a lot of the burned gases out through the ports before even encountering baffles. Could make for a very quiet weapon... if it's not a completely nonsensical idea.

It's already a pistol length gas system.

My best advice would be to build the suppressor the way you want it, then adjust your handloads accordingly. Not the other way around.

[John A.]

I can only go up more about a half a grain charge in my loads. So, let's pretend that porting the barrel is out because much more than that puts me over the supersonic barrier.

And not to mention, is getting around 53k psi chamber pressure according to the numbers I am getting.

While I would love to port the barrel, as I mentioned above, I don't think is feasible for this application. Cramming more powder in there to overcome the reduced dwell time, has more opportunity to go wrong than right.

[fishman]

I can only go up more about a half a grain charge in my loads. So, let's pretend that porting the barrel is out because much more than that puts me over the supersonic barrier.

Then change powders if you have to

[John A.]

I have worked these loads up because the "popular" blackout powders aren't worth a hoo-ey and I have experimented heavily to get to this point with the powders I am using.

These are clean burning, and noticeably a lot more quiet versus using the "popular powders" while using the same suppressor and no frp because the powder is already burned out before reaching the suppressor. You can't even see a puff of gas come out of the ejection port while reviewing the video afterwards.

Switching powders would be going backwards.

And thus why I am wanting to experiment with a high/low pressure expansion chamber.

I understand your point about porting the barrel into a reflex chamber. And with another load, or caliber, I would tend to agree with you. But that will not likely work in this application.

And if I did ultimately port the barrel, it would be one port at a time while ensuring that I wasn't sacrificing function. Regardless, I am very hesitant to even make one port. It took a lot of work to get it to fully cycle using the lightweight buffer and reduced power spring without the ports. It's right on the borderline of full function or not already and is why I am hesitant to touch the barrel.

[crazyelece]

Isn't subsonic blackout treated like a low pressure round?

I would pick a different platform with a higher starting pressure like .223 or .308 to try your idea or porting on

[Capt. Link.]

John great post!
A custom built brake will work better for reflex use.
#1 a multiple chamber one will strip more HP gas.
#2 do not hinder gas flow into the reflex chamber by supporting the brake at the forward end.
#3 use a sub-sized coaxial tube to direct gas into the rear of the reflex supported by the custom brake.

Don't blow off using barrel ports they can be very effective without altering gas port pressure or velocity to any significant degree.

-CL

[John A.]

Those are good ideas captain.

Do you think instead of a radial tube, that one could perhaps thread the inside of the cone chamber deeply enough to direct the flow back toward the reflex chamber?

Especially if you could position the groove over the muzzlebrake port(s)?

------------------------------------------------

Or, perhaps step the cone something like this:



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Or a combination of both:

[gunny50]

John,

You could combine ideas from yours with the De Lisle design


Gunny

[John A.]

The Delisle is my favorite integral of all time.

I have studied the blueprints a lot over the years.

[wquiles]

John great post!
A custom built brake will work better for reflex use.
#1 a multiple chamber one will strip more HP gas.
#2 do not hinder gas flow into the reflex chamber by supporting the brake at the forward end.
#3 use a sub-sized coaxial tube to direct gas into the rear of the reflex supported by the custom brake.

Don't blow off using barrel ports they can be very effective without altering gas port pressure or velocity to any significant degree.

-CL

Captain,

I like the ideas, but having difficulty with the visuals. So it would be a brake with two chambers:
- chamber closer to the muzzle would feed gases to a back reflex chamber
- front chamber feeds a traditional baffle stack

Fair to assume that there is no direct connection between the two chambers/sections? Gases in the reflex chamber would have to eventually go back through the ports and then exit into the forward cavity/chamber and of course into the baffle stack?

Will

[Hamond]

you can test your idea in the topic on one Russian forum. http://forum.guns.ru/forummessage/117/1951739.html
there guys offer their ideas and models and I do their calculations.

[Capt. Link.]

John great post!
A custom built brake will work better for reflex use.
#1 a multiple chamber one will strip more HP gas.
#2 do not hinder gas flow into the reflex chamber by supporting the brake at the forward end.
#3 use a sub-sized coaxial tube to direct gas into the rear of the reflex supported by the custom brake.

Don't blow off using barrel ports they can be very effective without altering gas port pressure or velocity to any significant degree.

-CL

Captain,

I like the ideas, but having difficulty with the visuals. So it would be a brake with two chambers:
- chamber closer to the muzzle would feed gases to a back reflex chamber
- front chamber feeds a traditional baffle stack

Fair to assume that there is no direct connection between the two chambers/sections? Gases in the reflex chamber would have to eventually go back through the ports and then exit into the forward cavity/chamber and of course into the baffle stack?

Will

The problem with reflex chambers is they are hard to fill.You could split the muzzle brake to feed the reflex and the primary chamber at the loss of needed gas pressure in the reflex side if of large volume.I would add small communication ports between the two chambers if a coaxial tube was used.This will reduce back pressure in the reflex side and allow it to fill while most of the gases will re-enter the brake assembly and travel through the suppressor.You could arrange the communication ports so they caused turbulence upon exiting the reflex side to theoretically increase suppression.

I've never seen any major gains in using reflex chambers over what can be achieved when the proper baffle and size are chosen to match caliber.A large volume will never make up for a poorly designed suppressor.

[KenHo]

John A. - you mention using a very fast burning powder (pistol?) for subs in your 300BO. I had wondered about that, seemed like a good idea, but everyone seems to be focused on the faster rifle powders. Would you mind sharing what powder you are using? What do you think about Unique?

A PM (or email) is fine if you prefer not to post.

Ken H>

[silverbulletexpress]

I don't post much so please excuse me for jumping into a technical thread without much introduction. I'm new to suppressor design but have done a lot of work with compensators and flash hiders.

I had the thought that if the goal is to direct as much gas as possible into the reflex portion then porting the barrel in that area might be counter productive. My reasoning is that since those ports are behind the muzzle they will flow gas into the reflex area sooner than gas that is exiting the muzzle device. So in effect the reflex area would be already have positive pressure which would offer resistance to the gases directed there from the muzzle device/chamber. I guess it's also a matter of timing. If there was a way to create a negative pressure to draw gasses from the muzzle device into the reflex area it seems that would be ideal but probably impossible. My thinking is that it's difficult to get much use out of the reflex area without creating a lot of back pressure. If I'm nuts just say so I have a thick skin.

[a_canadian]

As Capt. Link. has stated, a simple reflex volume over the barrel with a ported muzzle plug is only minimally useful in suppression. In my experience the greater benefit of such a design is in alignment, in cases where barrel OD or other factors do not easily permit one to use the shoulder for indexing on the bore for alignment with baffles. A few inches of reflex volume with an accurately cut rear plug fitting the barrel well behind the muzzle can make for relatively easy alignment. If one then drills a few holes in the barrel, say 2" back from the muzzle to preserve accuracy but not too far back to preserve velocity of the projectile, a preliminary dumping of high pressure gas flow into that reflex volume will considerably enhance suppression, over and above whatever the baffles are doing. Going even further, porting the barrel well back through the reflex volume, will both further enhance suppression efficiency and reduce projectile velocity. So trade-offs, among which each of us must weigh which we are willing to make.