Sound moderator

[Jsun 0]

Hi everyone. Just wondering if anyone has used a .17HMR with, and without a sound moderator.. does it affect the zero? Is it much louder without? I used a friends Valquartsen on a prarie dog hunting trip in June this year. It did not have a mod, only a muzzle break, but it did not seem much louder than my HMR with a mod. Any replies appreciated.

 

Thanks, Jsun.

[matt_hooks 188]

A moderator will only reduce noise caused by the expanding gases from the powder burning. On a .22 firing subsonic ammunition this is where most of the noise comes from and so a moderator can make a huge difference.

 

With a centrefire, there is a lot of powder being burnt, and so again a moderator will have a noticeable effect.

 

With the .17, there's not a huge amount of powder being burnt, so most of the noise is the sonic shockwave of the round moving through the air at supersonic speeds. A moderator can do nothing to prevent this, and so doesn't have a massive effect on the noise level of a .17 (although this depends on the make of mod of course, as you can remove SOME noise by allowing the exiting gas to expand in a confined space rather than in plain air.

[Jsun 0]

A moderator will only reduce noise caused by the expanding gases from the powder burning. On a .22 firing subsonic ammunition this is where most of the noise comes from and so a moderator can make a huge difference.

 

With a centrefire, there is a lot of powder being burnt, and so again a moderator will have a noticeable effect.

 

With the .17, there's not a huge amount of powder being burnt, so most of the noise is the sonic shockwave of the round moving through the air at supersonic speeds. A moderator can do nothing to prevent this, and so doesn't have a massive effect on the noise level of a .17 (although this depends on the make of mod of course, as you can remove SOME noise by allowing the exiting gas to expand in a confined space rather than in plain air.

[Jsun 0]

A moderator will only reduce noise caused by the expanding gases from the powder burning. On a .22 firing subsonic ammunition this is where most of the noise comes from and so a moderator can make a huge difference.

 

With a centrefire, there is a lot of powder being burnt, and so again a moderator will have a noticeable effect.

 

With the .17, there's not a huge amount of powder being burnt, so most of the noise is the sonic shockwave of the round moving through the air at supersonic speeds. A moderator can do nothing to prevent this, and so doesn't have a massive effect on the noise level of a .17 (although this depends on the make of mod of course, as you can remove SOME noise by allowing the exiting gas to expand in a confined space rather than in plain air.

Sorry.. i pressed the wrong button!! I meant to ask, would the moderator slow a bullet enough to affect zero?

[SNAP SHOT 194]

the mod, does not slow the velocity of the bullet, and the only thing to effect the zero with be the weight of the mod on the end of the barrel

effecting the harmonics of the barrel, and therefor changing the zero or point of impact.

 

think of the waves coming into the beach at regular intervals say for instance 10 seconds apart, this is the same as the bullet travelling down the barrel it creates a wave and when that wave reaches the weight ( the moderator) where the mods on the barrel this wave pattern will change, and the zero of the bullet will therefor change.

 

Snap.

[Jsun 0]

Snap.. thanks for a great reply. I think i will try my rifle without the moderator.

[Treacle Trackpad 6]

Couple of things to consider, firstly, when you're on the prarie there are very few things for sound to bounce back to you from, therefore it won't seem as noisy as when in a farmer's field with boundary hedges all round you. Secondly, a moderator will help to contain the expanding gasses at the muzzle which can de-stabilise a bullet as they overtake it, this can aid accuracy.

 

This said, if I could shoot without a mod I would

[Jsun 0]

Couple of things to consider, firstly, when you're on the prarie there are very few things for sound to bounce back to you from, therefore it won't seem as noisy as when in a farmer's field with boundary hedges all round you. Secondly, a moderator will help to contain the expanding gasses at the muzzle which can de-stabilise a bullet as they overtake it, this can aid accuracy.

 

This said, if I could shoot without a mod I would

Yes, you're right.. there was maybe a slight hill that sound could bounce off, otherwise there was mile upon mile of open space on the prarie. I will try my gun at 100yds with, and without the mod as soon as i get time.

[jamie g 17]

well you wont stop the sonic crack. a hmr with out mod on it makes a hell of a noise. your be very surprized how much a mod cuts it down. yes you still get thta snap. but the over all boom is much less

[danebrewer10 6]

without the mod it is whole bunch louder! if you're shooting in a valley, it sure does roll up and down especially if the air is cold and still the mod does change the POI fairly significantly, I guess it sounded quiter as there were no surfaces for the sound to reflect off of back to you, unmoderated you do get a sting in your ears after a couple of shots, so not really recommended, I do have to ask the question as I bet others have been thinking it.... why the muzzle brake on an HMR? (apart from looks of course) that'd direct the blast more towards you i'd have thought?

[Jsun 0]

Here's a picture of me on the prarie with my friends Volquartsen, and a prarie dog i shot at 167 yds. The muzzle brake is purely for cosmetic reasons. The muzzle blast tends to exit from the sides, rather than back towards you.

[danebrewer10 6]

oh right, I always thought muzzle breaks funneled the blast backwards to mitigate the force of the recoil of the gun

[dadioles 68]

I cannot help wondering if those people who suggest that fitting a moderator to a .17HMR makes very little difference have ever used an HMR?

A moderator makes a huge difference.

Without a moderator there is a loud boom sufficient to make your ears ring and require ear protection.

With a moderator the boom is hugely reduced and no ear protection is really necessary. It is also much more neighbour friendly although arguably a little less exciting!

There is nothing you can do about the sonic crack as the bullet passes through the sound barrier as that happens after it has left the barrel.

I have found that the moderator does affect the trajectory. My Anschutz shoots 2 inches higher at 140 yards without the SAK moderator fitted although there is no lateral movement.

Les