With a silencer on your rifle you are getting a number of advantages.
The most obvious is of course that the noise is reduced.
Other advantages are that both recoil and muzzle-flash is heavily reduced which gives a more comfortable shot with a reduced barrel-rise and preserved night vision when shooting in poor light conditions – perfect when hunting wildboar at night for example.
Another advantage with a silencer is that the rifle gets a weight on the barrel which creates a better stability when shooting on still targets and, which most shooters experience, a more controlled “swing” when shooting on moving targets.
A silencer reduces the gas pressure by expanding the burning powder gas into one or more chambers inside. The bullet acts as a moving valve that sequentially releases the pressure as the bullet passes the chambers. When the bullet leaves the silencer, the following gas will flow out of the silencer at a reduced speed and over a longer time which results in a reduced sound pressure. A good example of the difference between shooting with and without a silencer is the difference in noise when opening a champagne bottle by either “shooting” the cork or holding it and slowly releasing the pressure.
A silencer can only reduce the noise created by the burning powder gases. When the bullet speed is higher than approx. 340 m/s (1125fps) it passes the speed of sound in air and a supersonic bang is created in the same way as when a plane passes the “sound barrier”. The noise of the supersonic bang is approx. 140dB measured at a 90 degree angle and at a distance of 1 meter from the bullet trajectory.
No silencer can reduce/eliminate the supersonic bang!
With subsonic ammunition the impression of the silencer is that it is extremely efficient thanks to the fact that there is no supersonic bang created.
Depending on calibre and barrel length the combustion is done fully or partially inside the bore of the barrel. A big muzzle flash indicates that there is powder burning outside the barrel. With a silencer the powder will be burnt and/or extinguished inside the silencer which heavily reduce or eliminates the muzzle flash.
The recoil is reduced by the fact that the forward moving gases is being stalled inside the silencer. If it was not fixed through the thread on the barrel it would simply fly forward and that is the force that creates the recoil reduction. There are also opposite directed forces that limit how much the recoil can be reduced such as the weight of the bullet acceleration forward creating the “kick” in the opposite direction. A rule of thumb is that the recoil is reduced with 25-40% when shooting with a silencer.
A well-manufactured and symmetrical silencer, fitted correctly on a normal barrel creates better grouping but the point of impact is slightly lowered. The weight of the silencer reduces the barrel vibrations which increases the accuracy. The fact that the point of impact normally is lowered depends mainly of the fact that the barrel rise is reduced and that the recoil is absorbed by the shoulder. Since the bore is normally not aligned with the shoulder there is a torque created that wants to lift the barrel, but the weight (silencer) is counteracting this force and makes the barrel point lower i.e. a lower hit than without silencer.
The pressure in the silencer is high and push the bullet forward through the silencer. The only resistance the bullet meets inside the silencer is air or gases from the previous shot. The pushing gas will therefore accelerate the bullet to an higher speed than without a silencer. An increase of 5-10m/s is not unusual.
Different designs of silencers
There are two main designs of silencers:
- “Muzzle mounted” (where the whole silencer apart from the thread is adding to the barrel length.
- “Over barrel/Reflex”- slides over the barrel and has a portion of the expansion chamber behind the barrel opening.
In general, a muzzle mounted silencer is more efficient in relation to its size compared to an over barrel version, but it can be perceived as it makes the rifle a bit long and “front heavy”
The advantage with the over barrel version is that it is normally perceived as non-obtrusive on the rifle as it normally adds a shorter length to the barrel than the muzzle mounted version.