Thread: Suppressors - Am I missing something

4 bloody pages of theoretical bumph! The question was about internal muzzle brakes in suppressors. The answer is that all suppressors have a recoil reducing effect by virtue of their baffles providing an impingment surface to the muzzle gases, tending to put forward pressure in the suppresor. Over-barrel suppressors do have an effective muzzle brake system, which is the internal part that screws onto the barrel. This is a muzzle brake in basic design and is used to divert the muzzle gases into the rear part of the suppressor (where they expand and cool at a much lower pressure). The baffles in the front part play a much lesser role in reducing recoil as the gas pressures are much lower. The internal muzzle brake in over-barrel units is usually efficient enough to counteract the bolt cycling in semi-autos, requiring some tuning of the gas system for reliability. For the lesser informed, muzzle brakes work by trying to pull the firearm forward when the expanding muzzle gases strike the forward surfaces of of the vents. Vents in the top also help to counter muzzle rise in the same manner. That is all there is to it.

There has been more psuedo-scientific garbage written (and claimed) about suppressors than you can shake a stick at. I have commercially designed and manufactured thousands of suppressors for all types of firearms since the early 1970's. Suppressors rely on only three factors for efficient operation; accurate alignment with the bore, an efficient (but simple) baffle design, and sufficient internal volume to contain most of the muzzle gases. Any claims outside of these parameters are dubious at best!

Originally Posted by gundoc

For the lesser informed, muzzle brakes work by trying to pull the firearm forward when the expanding muzzle gases strike the forward surfaces of of the vents.

Yes but if the gas can't instantly escape the ports into the atmosphere without hitting anything its effectiveness is lost.

As witnessed by placing covers over brakes with or without airspace around them.

Originally Posted by Kiwi Greg

Yes but if the gas can't instantly escape the ports into the atmosphere without hitting anything its effectiveness is lost.

As witnessed by placing covers over brakes with or without airspace around them.

True, the efffect is lost to some extent (but far from completely) if the brake is enclosed, which is why over-barrel suppressors have the tube behind the brake to give the gases somewhere to go and expand.

Originally Posted by gundoc

True, the efffect is lost to some extent (but far from completely) if the brake is enclosed, which is why over-barrel suppressors have the tube behind the brake to give the gases somewhere to go and expand.

Yes as the gas comes back it hits the suppressor pushing it back negating its recoil reducing effect.

This one is inside a magnum suppressor & has about 125mm behind it.

Originally Posted by gundoc

4 bloody pages of theoretical bumph! The question was about internal muzzle brakes in suppressors. The answer is that all suppressors have a recoil reducing effect by virtue of their baffles providing an impingment surface to the muzzle gases, tending to put forward pressure in the suppresor. .......

....There has been more psuedo-scientific garbage written (and claimed) about suppressors than you can shake a stick at. I have commercially designed and manufactured thousands of suppressors for all types of firearms since the early 1970's. Suppressors rely on only three factors for efficient operation; accurate alignment with the bore, an efficient (but simple) baffle design, and sufficient internal volume to contain most of the muzzle gases. Any claims outside of these parameters are dubious at best!

@gundoc,

With all respect for your conclusion which I can only agree with, you are harsh on other contributors, even arrogant... and in karmic fashion immediately plunge neck-deep into the bog of your version of Munchausen's pigtail self-lift.

To paraphrase your first bit, when a car passenger kicks the dashboard the car pulls forward. We all know this is false. The explanation is that the passenger supports his back against his seat, so the effect of his forward blow against the dashboard is entirely cancelled by his rearward action against his seat as both objects are fixed to the car. It must be understood that the gun and silencer are attached to each other. They are a single unit; the silencer is part of the gun. A blow from a gun against itself (in the form of impingement of its gases against its own baffles) will not pull it forwards.

Astronauts on a spacewalk similarly can not propel themselves through space by slapping their own butts.

Originally Posted by Cordite

@gundoc,

With all respect for your conclusion which I can only agree with, you are harsh on other contributors, even arrogant... and in karmic fashion immediately plunge neck-deep into the bog of your version of Munchausen's pigtail self-lift.

To paraphrase your first bit, when a car passenger kicks the dashboard the car pulls forward. We all know this is false. The explanation is that the passenger supports his back against his seat, so the effect of his forward blow against the dashboard is entirely cancelled by his rearward action against his seat as both objects are fixed to the car. It must be understood that the gun and silencer are attached to each other. They are a single unit; the silencer is part of the gun. A blow from a gun against itself (in the form of impingement of its gases against its own baffles) will not pull it forwards.

Astronauts on a spacewalk similarly can not propel themselves through space by slapping their own butts.

Attachment 76413

100% correct. As stated it is a closed system.

You must look at it from an external point of view in order to make sense as I stated earlier. The reduction in recoil from a suppressor can only come from the reduced gas emission speed from the muzzle (which is now the end of the suppressor) and the extra mass added to the system. It is only when something leaves the system (the projectile and gases leave the muzzle) that the conservation of momentum is applied. This will give the initial speed and hence energy of the recoil. @gundoc, this is simple high school physics.

Originally Posted by Cordite

@gundoc,



To paraphrase your first bit, when a car passenger kicks the dashboard the car pulls forward. We all know this is false. The explanation is that the passenger supports his back against his seat, so the effect of his forward blow against the dashboard is entirely cancelled by his rearward action against his seat as both objects are fixed to the car. It must be understood that the gun and silencer are attached to each other. They are a single unit; the silencer is part of the gun. A blow from a gun against itself (in the form of impingement of its gases against its own baffles) will not pull it forwards.


Attachment 76413

Two points, 1) there is an effect with the energy transfer in your example- the seat resists the rearwards force at the same rate with that the dashboard resists the forwards force. A better example the person bouncing between the seat and the dashboard hitting them at different times thus producing a rocking motion. Yes the silencer and gun are attached but the gas that hits the brake portion and are forced rearwards are given moments to cool and slow thus the speed with which they hit the rear of the suppressor tube is reduced. If a gas hits the front with a high speed and is forced rearwards within the can then hits the rear of the can with a reduced speed due to the cooling and turbulence encountered, then both ends are not subjected to equal countering forces.

And as a final note, the air thrust forward in your cartoon has been shown to actually work. Poorly but with some gain in forward momentum. Mainly due to the same aerodynamic principle that means an anemometer works. The dome shape at the front resists the air less than the shape behind it.

Originally Posted by timattalon

And as a final note, the air thrust forward in your cartoon has been shown to actually work. Poorly but with some gain in forward momentum. Mainly due to the same aerodynamic principle that means an anemometer works. The dome shape at the front resists the air less than the shape behind it.

@timattalon,
Yes, blowing into a large sail with a big fan actually can produce a forward drive. I saw that Mythbusters episode, and it was really good they bothered to test it as the result was forward motion of the craft!!! The reason for this apparent miracle is that the sail deflected the blast of the fan sideways and rearwards. I.e. it nevertheless still illustrates an open system, not an enclosed system like a muzzle brake enclosed in a can and unable to ultimately direct blast in other directions than forwards.

Originally Posted by Cordite

@gundoc,

With all respect for your conclusion which I can only agree with, you are harsh on other contributors, even arrogant... and in karmic fashion immediately plunge neck-deep into the bog of your version of Munchausen's pigtail self-lift.

To paraphrase your first bit, when a car passenger kicks the dashboard the car pulls forward. We all know this is false. The explanation is that the passenger supports his back against his seat, so the effect of his forward blow against the dashboard is entirely cancelled by his rearward action against his seat as both objects are fixed to the car. It must be understood that the gun and silencer are attached to each other. They are a single unit; the silencer is part of the gun. A blow from a gun against itself (in the form of impingement of its gases against its own baffles) will not pull it forwards.

Astronauts on a spacewalk similarly can not propel themselves through space by slapping their own butts.

Attachment 76413

I am well aware that you cannot stand in a bucket and pick it up by the handle, however my comments are backed up by years of experimentation and manufacture (probably more than any current manufacturer). Suppressors are not a 'closed system' and, despite the efficiency of any baffle system, a decent percentage of the gases exit the muzzle in front of, and behind, the bullet. I guess I will just have to set up an experimental pendulum (friction free as opposed to a slide) and publish the results of the recoil dampening effect of various suppressors and muzzle brakes.

I don't intend to be harsh on individual opinions but I have heard too much garbage and pseudo-scientific rambling on the subject of suppressors over the years, and it irritates me!