How do integral suppressors work?

[cliffy109]

Yes, this is my first post and it is probably something that is common knowledge but I've been googling for an hour and can't find an answer. My basic question is about how an integral suppressor works. Let's use a bolt action rifle for instance. If the overall length of the barrel is 20", does it mean that there is only rifling for the first 12" or so and the rest is the suppressor components? Or does the threaded part of the barrel extend nearly the full length of the barrel and gasses get vented back like a reflex suppressor near the end? One other possibility in my head was that there may be small holes cut at various points down the rifled bore to bleed off small bits of the expanding gasses before finally ending near the end of the barrel.

That last way makes the most sense in my mind, but there is probably a good reason why it doesn't work like this.

Here's what I'm considering: I have a Steyr Scout rifle that I would really like to suppress without adding too much to the length or weight and I'd like to keep velocities up. The barrel is currently 19" and pencil thin with flutes. Cutting it back to 16" and adding a 5" can might be the best solution, but it just seems to me that one could start venting off the gasses before that.

[John A.]

There are actually several methods that I think you are referring to. But they are all different.

An integral slides back over some (or all) of the barrel. While it is possible to use the barrel as a makeshift baffles like the old 77/22



Another effective way to use an integral is to drill holes and port the barrel so some of the gasses are directed into the reflex portion of the can. Like this:

http://specialoperations.com/28973/de-l ... en-reaper/

There is another method which is more often referred to as a REFLEX suppressor. They are not ported from the barrel, but some of the gas can expand rearward over the barrel from the expansion chamber.

Since a picture is worth a thousand words:

http://www.reflexsuppressors.co.uk/

Or, you can use your favorite parts of all 3 of the above.

[cliffy109]

Thanks for the reply. I had looked at that site on the reflex suppressors and a few others which led me to believe those are not a really good option. The rifle for which I am researching is the Steyr Scout which has about 7" of barrel sticking out of the rail/stock section of the gun. From the reading I did find, everybody seems to be in agreement that a reflex suppressor isn't very good at suppressing sound or at least not as good as a conventional screw-on can. That got me to thinking about venting the barrel in the rifling area.

Anyway, I think you answered my question about how integral suppressors work. I may contact a couple of suppressor manufacturers to see if they have any ideas on how to go about this on this particular rifle. Might be a lot more expensive than I'd like, but I'll do some checking.

[John A.]

I'm not really a fan of reflex cans. Just seems like a lot of wasted space to me. I know many in Europe like them. But I like a ported integral much better. They are more effective. I believe that if for no other reason at all, bleeding some of the gas into the integral section is less gas that the baffles have to deal with initially.

This is also especially helpful on certain bullets where you can drop the velocity below the speed of sound (1115 fps or so), but that's getting way away from rifle caliber velocities. I'm talking in general more about some handgun calibers now and I don't want to get too far from the subject at hand.

[cliffy109]

Cool. Thanks. Who makes such a thing?

[John A.]

Check with Curtis Tactical.

They are a member here and often make custom designs. Many of which lately have been integrals.

[DKDravis]

Steyr Scout -- suppressed Can/Reflex/Integral-- been there ..

The original .308 Steyr Scouts really do have a "pencil-thin barrel" - I have custom made a few adapters, to allow the use for both normal and reflex cans on them. There really is not enough material in the original barrels to cut a proper shouldered thread in any standard thread size.

What I did was cut a custom thread and then make up an adapter with a very tight thread fit + hard Locktite - then turn the combined barrel and adapter with a proper shoulder and threading -- to get a properly aligned threading and right angled shoulder- aligned with the barrel bore. The Steyr Scout "pencil barrels" are hammer forged, and the outsides are not well aligned.

Making an integral poses a problem in that there really is not a lot of room for additional barrrrel diameter inside the hand-guard/front stock. .. The most effective in terms of reducing sound on the Scouts I have seen, were reflex cans that added around 4" to the overall length.

[fishman]

Why not just shoulder on the muzzle like a 1911

[cliffy109]

Steyr Scout -- suppressed Can/Reflex/Integral-- been there ..

The original .308 Steyr Scouts really do have a "pencil-thin barrel" - I have custom made a few adapters, to allow the use for both normal and reflex cans on them. There really is not enough material in the original barrels to cut a proper shouldered thread in any standard thread size.

What I did was cut a custom thread and then make up an adapter with a very tight thread fit + hard Locktite - then turn the combined barrel and adapter with a proper shoulder and threading -- to get a properly aligned threading and right angled shoulder- aligned with the barrel bore. The Steyr Scout "pencil barrels" are hammer forged, and the outsides are not well aligned.

Making an integral poses a problem in that there really is not a lot of room for additional barrrrel diameter inside the hand-guard/front stock. .. The most effective in terms of reducing sound on the Scouts I have seen, were reflex cans that added around 4" to the overall length.

Hmmm.... I was afraid I was going to run into something like this. This is where I was thinking of a hybrid between an integral and a reflex. The handguard/rail section extends quite far forward, but there is about 9" of barrel sticking out past that point. That is also the point where the barrel flutes begin, although there is a very short (like 1/2") of non-threaded section in front of the handguard. If that were to be threaded for a long, slide-over can, this might be a start.

If one were to drill small holes along the length last 9" of the barrel and use the rear section for an attachment point, that seems like it might work. It wouldn't be a true "reflex" because gases would not be directed 180 degrees backwards and it isn't truly integral either. Am I on the wrong track or has this been tried?

[DKDravis]

Given the configuration of the original Scout barrel, you could probably turn down the front portion of the flutes, up to the short full profile section, then shorten the barrel a bit and thread at the unfluted section.

Cutting holes in the front part would effectively shorten the barrel, giving you a reduction in muzzle velocity comparable to shortening the barrel almost to the same length. I would get these holes cut by EDM, to avoid messing up the rifling on the inside.
The hammer forged Steyr barrels seem to be harder than normal barrel steel, and do not machine very freely or nicely.

You could probably build an effective "Semi-integral" suppressed barrel this way. I personally do not like shortening a .308 below 16-18" - and definitely not for use without a more or less permanent suppressor .. .308 is quite loud enough in a 20" tube IMHO--

I assume you know how to disassemble the Scout and how to remove the barrel from the receiver? (You need a custom made tool for that to get to the castellated nut holding the barrel) Once removed the Steyr barrel is easy to work on.

My favorite is my .376Steyr "Dragoon" -- (Jeff Coopers name for the "big Bore Scout) - I have threaded this one M14 x 1 at the muzzle and use an A-TEC Carbon S2 reflex can on it .. It works extremely well with custom made 320 grain .375 bullets propelled at 1110 ft/sec by Trailboss ..

[cliffy109]

Thanks DK. This is exactly the kind of thing I needed to know. I agree that anything shorter than about 16" is just too short for keeping .308 projectiles moving at a proper hunting speed. I was unsure what the effect of a series of holes might do and from your observations, it likely isn't a smart way to do it.

Based on this, it sounds like the most effective way to keep things short and light is to shorten the barrel to 16" and thread it for one of the smaller .308 cans out there like the Crux Nemesis or Thunder Beast CB5. It wouldn't be as slick looking but should stay fairly close to the original idea of a Scout rifle.

Oh and I realize this is not "on topic" but I had a spare stock for this rifle and I removed the bipod which saved about half a pound. I added a little of that back by filling in the gaps with gray JB Weld and sanded it down smooth. The result is a considerably lighter and more trim rifle. If I can keep the suppressor under 10 ounces, the total package weight including scope, sling and empty mag will be 7.75 pounds. I would have liked to keep the overall length below 40 inches but I don't think that is possible without sacrificing too much velocity.

And finally, I once owned a .376 Steyr version of the Scout. It was a crap-load of fun but there is about zero chance I would ever need such a beast so I sold it a few years ago when I was desperate for cash.

[DKDravis]

And finally, I once owned a .376 Steyr version of the Scout. It was a crap-load of fun but there is about zero chance I would ever need such a beast so I sold it a few years ago when I was desperate for cash.

Ha-ha!

I did just the opposite, sold off the .308 -- The 376 can be handloaded to cover virtually any of my hunting needs - and then some -

I reload for a friends 376 -- He has shot everything from red fox to Cape buffalo with it -- (Old stock of 300 grain Speer AGS Tungsten core solids @ 2300fps ) With the right handloads the 376Steyr can be a seriously hard hitter ..