Well, one thing I am not is an expert on the internals of suppressors. If any are designed to divert the directional vector laterally, then you could get more of this effect. The few suppressors I have seen cut open (on the inter-webs) do not seem to be built in that fashion, but that does preclude some built to divert gases orthogonal to the direction of fire. There ARE spring/weight dampers - my ignorance may be showing here: I understood most "suppressors" were simply sound abatement devices. (See the end notes for more on these).
If you are bored by ballistics and simple equations, skip the rest of this post.
Early in the process of learning Physics, we are trained to listen for references to 'fictitious' or 'pseudo' forces - things that are not there. For example, when you swing a weight on a string if 'feels' like the weight is pulling back on the string. No such thing. The weight is simply trying to go in a straight line. (Albeit, while forced to travel in a curve.)
Similarly, one does not need to do any equations to line draw the directional forces in a rifle. The explosion can only exit in one direction, thus the force is in the opposite direction. Enter porting and this changes. Some of the gases are ejected laterally and that DOES change the force going backwards.
FlyGuy said:
The best way I can describe it to people is that the gun "Bounces" more then kicks.
And as can clearly be seen in the picture of the Silencer Co Harvester, this has lateral ports - none of the suppressors I see in LGS have these ports. I am ignorant regarding the popularity of ported suppressors and sound abatement only suppressors.
https://silencerco.com/silencers/harvester/
As I said, I can claim no expertise WRT suppressors, but again Physics comes into play. It seems that the primary design of most suppressor has nothing to do with escaping gases and everything to do with dampening the sound percussion (the effect of air being rapidly compressed by the explosion both within the chamber and as the projectile and hot gases exiting the barrel.) These compressions on the air around the exit cause a series of vibrations in a frequency we experience as sound. The intent of a suppressor is to dampen these oscillations and thus reduce the sound. But the sound being created by the explosion should be mostly omnidirectional - and thus the dampening should be omnidirectional.
The force from the sound itself is negligible - The process by which sound propagates in the air dampens the force as the inverse square of the distance. I have never seen anyone measure the sound of riles, but this chart looks basically correct:
https://www.thehighroad.org/index.php?t ... ns.646806/
According to these data, a .30-06 rifle normally creates 160 dB - and that seems about right. If you tried to capture the effect of that sound as air pressure pointed back towards the shooter, it would not move a toddler backwards. (Say by placing a light piece of plywood and measuring the instantaneous pressure caused by the sound itself.)
One reason good suppressors do not seem to cause directional errors in the bullet flight is that the sound is so much slower than the bullet. (Older suppressors relied upon gaskets, which touched the bullet - bad idea and they DID slow things down, as well as cause serious accuracy errors - new suppressors do not touch the bullet.)
The nominal speed of sound in dry air and sea level is 767 mph (I am doing this in miles and feet since most of our forum members seem to be Americans ;-)
(767 miles/hour * 5280 ft/mile) / 3600 seconds/hour = 1,125 feet/second = speed of sound.
A .30-06 bullet exits the barrel at between 2,700 f/s and 3,300 f/s. Even at 1000 yards, the bullet is traveling 75 f/s faster than sound.
Thus, inside a suppressor, the "sound" is being dampened after the bullet is gone, because the sound propagates at 1125 f/s and the bullet moves more than twice that fast on exit.
Again, YYMV, some clever designer may have found a suppressor enhancement that uses lateral gas direction as an agent to baffle the sound. In this case, I would expect some noticeable sideways gases discharging from the suppressor - I lack the experience to comment on this. All the suppressors I have handled in a gun store seemed heavy to me. I looked up a couple online and the weight seems to vary from 10oz (283 grams) and 14 oz (396 grams). In addition a 7 inch (18 cm) suppressor adds 1/3 the length of a 22 inch (56 cm) rifle barrel and we begin to see Archimedes' leverage ("Give me a lever long enough, and a place to rest it, and I will move the earth.")
Suppressors add mass and leverage at a critical point in the barrel geometry. Frankly, it would take a lot of work in a good lab to isolate all these forces, and I have not found any research of it having been done. People seem to buy a "net effect" in a suppressor, and the benefits, while possible to measure in isolation, seem to combine in subjective ways.
One thing I have found for certain in years of examining ballistics tables: bullets are pure Newtonian Physics. You can derive the air resistance directly from the velocity loss over time (gravity does not slow a bullet down, it just makes it fall). And you can exactly match the rate of fall with the gravity equation, modulated by the changing rate of bullet flight. The only ammunition that does not follow these rules is closely spaced shotgun pellets, which seem to create some interference amongst each other as they travel.
CAVEAT: There are people who have decades more experience with actual suppressors than I do. Some may have been engineered for exactly the effects noted above - but I cannot find them.
Here is an example of a 'recoil suppressor' that is based on increasing mass and length as well as adding a spring shock absorber:
http://www.mercuryrecoil.com/suppressors/index.htm Basically, these work because the fontal weight (mass - a chunk of metal) resists changing direction. This compresses the spring, which conforms to Hook's Law (f(x) = -Kx^2) - and the compression takes time, then it uncompresses and the mass returns to its origin point. This could account for the BOUNCE effect reported above - see if your suppressor has a spring in it (I don't think the Harvester has a spring.)
Important, these do not LOWER the recoil, they slow it down, which has the same subjective effect. You will still experience the same total recoil, just spread over more time.
(Side gas ports/brakes can actually reduce rearward recoil - springs cannot, but slowing down recoil feels like reduction.)
But any suppressor that is focused 100% on sound abatement should have the recoil reduction limited soley to the length+mass increase.
If you have a suppressor that combines both sound abatement and perceived recoil, my guess is that it has both springs and weights inside - or the porting devices. In order for the spring/weight combination to do any good, there is a technical term we would use for the mass: "a heavy sucker". A spring and a light damper weight would not change perceived recoil. So if you have an effective spring/weight recoil damper, I would venture it is heavy. If it is ports, they would have to be big to work on a rifle, and you can see the large ports on the Harvester.