Thread: kick arse suppresor ?

Hi guys and girls, I am about to run out of super low velocity 22 ammo ( 770fps) and it looks like any more will be pretty hard to come by. I made the mistake of going into humping and bitching in palmy the other day to see if they had any or were going to get any in. Basically they replied with a No, No, No and given their attitude I decided any more talk would have been wasted so went out the door. I don't mind a trip to Welly but see guncity has almost no cci segmented very low velocity stuff either.

So, seeing as I have a metric shit ton of CCI subsonic 1050fps stuff, has anyone tried a very large suppressor to get the sound down to a similar level as the 770 fps stuff ?. The neighbours know I shoot possums, Starlings etc... but I am keen on them not hearing me actually shooting so like the super quite stuff.

I am shooting mainly out of my model 2 BRNO with a "normal" suppressor on but the cci stuff still makes a bit of a crack ( much to the excitement of the AOS as mentioned by me previously ).

Sorry for the overly long bleat

DPT with extra baffles

End of story

Originally Posted by 7mmsaum

DPT with extra baffles

End of story

This.

I just use my standard centrefire overbarrel DPT that i run on my 223's, i have tried it with a couple of extra 22 cal baffles on it on the 22lr with cci subs and you cannot really hear the shot, but you certainly hear the thud of the projectile hitting its small game target.

Every now and again i find that a random sub does give a crack, so obviously it's one that's just supersonic

Originally Posted by 7mmsaum

DPT with extra baffles

End of story

Normally say yes but not sure if DPT makes a magnum in 22 line. The magnum centrefire is sublime for sound suppression. Friwi will conjure up a can for you.

I tried a big long centrefire suppressor and it was good with subs but still cracked with supers....if you getting crack...you going supersonic. NO suppresser will fix that.

Oh I thought 1050 fps was still subsonic ?
When I say "crack" it's probably just noticeably louder than the 770fps stuff which sounds more like a air rifle level of noise

Originally Posted by rugerman

Oh I thought 1050 fps was still subsonic ?
When I say "crack" it's probably just noticeably louder than the 770fps stuff which sounds more like a air rifle level of noise

My new 22semi is ultra quiet running cci subs and a gunworks fat 22 suppressor, the bolt cycling is louder than any muzzle report

Originally Posted by rugerman

Oh I thought 1050 fps was still subsonic ?
When I say "crack" it's probably just noticeably louder than the 770fps stuff which sounds more like a air rifle level of noise

Yeah, the CCI Quiet ammo is definitely quieter than other subsonic ammo. I have also tried Fiocchi Long Z (I think!), it is quieter than most at 850fps but still louder than the CCI segmented.

Apparently the first shot of a string is louder due to the "pop" of the oxygen inside the suppressor burning off.

Originally Posted by rugerman

Oh I thought 1050 fps was still subsonic ?
When I say "crack" it's probably just noticeably louder than the 770fps stuff which sounds more like a air rifle level of noise

What altitude do you shoot at? My mate in Twizel has a problem with most subsonic brands as the speed of sound is slower at altitude due to the less dense air, so many subsonics are not subsonic in the High Country. I can't recall which subsonic brand he finally decided was reliably subsonic for him, may have been CCI.

If the issue is "enough suppressor", have you tried shooting the suppressor wet? Detach, pour in water and empty it out, reattach, first couple shots are significantly quieter. I super-tuned a small steel suppressor with wire rolled mesh which would retain more wetness. Other option is to use KY gel, this basically will coat the inside of the suppressor with more water than it usually would hold without it squelching about. The water is SUPER effective at absorbing heat from the gases, remember back in science classes about something called "latent heat of vaporisation".

6 minute video, jump to 4 minutes for the bare bones and comparison.

Originally Posted by Cordite

What altitude do you shoot at? My mate in Twizel has a problem with most subsonic brands as the speed of sound is slower at altitude due to the less dense air, so many subsonics are not subsonic in the High Country. I can't recall which subsonic brand he finally decided was reliably subsonic for him, may have been CCI.

Interesting, because air density has virtually nil effect on the speed of sound. Temperature is the condition that has most affect.

Had issue with CCI subs going supersonic every now and then in my Brno model 2 ,mentioned it to the gunsmith he suggested cleaning the barrel and it worked,apparently the build up of wax from .22 rounds can make the od bullet go faster due to more back pressure or something.worth a shot..

Originally Posted by Hunter_Nick

Interesting, because air density has virtually nil effect on the speed of sound. Temperature is the condition that has most affect.

Thanks. Yes, that is indeed correct. I'll pass it on to my mate, he may have done his tests in the very cold Twizel winter (24/7 hoar frost for weeks on end) and camr to draw the wrong conclusion that it was to do with altitude alone.

Still, his observation remains, that only one brand was reliably crack-free, the others too close to the sound barrier to perform well in NZ-encountered conditions of lower sound velocity.

Originally Posted by Hunter_Nick

Interesting, because air density has virtually nil effect on the speed of sound. Temperature is the condition that has most affect.

Yes, but temperature drops as altitude increases, so there is an indirect effect of altitude.
I read something in a hunting or tramping book years back that stuck in my brain - if I recall correctly, it said temperature drops 6.5 degrees for a 1000m increase in altitude, meaning the temp at the treeline is roughly 8 degrees lower than at sea level, all else being equal.

Originally Posted by Cigar

Yes, but temperature drops as altitude increases, so there is an indirect effect of altitude.
I read something in a hunting or tramping book years back that stuck in my brain - if I recall correctly, it said temperature drops 6.5 degrees for a 1000m increase in altitude, meaning the temp at the treeline is roughly 8 degrees lower than at sea level, all else being equal.

Yeah but some people get confused because in aviation you have Indicated Airspeed and True Airspeed (IAS and TAS). Airspeed indicators rely on pressure, so as you go higher your TAS increases relative to your IAS. So at 0 alt, the speed of sound is around 660 knots (IAS and TAS ), and at 50000 feet it is ~ 570 knots TAS (due to the temperate drop) and 285 knots IAS (due to the temperature drop and decreased pressure reading).

And for some reason this gets crossed over into the belief that pressure has an impact on the true speed of sound (in air).

Originally Posted by rugerman

Oh I thought 1050 fps was still subsonic ?
When I say "crack" it's probably just noticeably louder than the 770fps stuff which sounds more like a air rifle level of noise

The speed won't be exactly what it says on the box. From the few brands of subsonic ammo I've chrono'd you can easily get +- 50 fps. Shooting subs, my .22LR rifle with a suppressor is quieter than any break barrel air rifle I have (which is quite a few)