So, subsonic ammo out of a Ruger 10/22 is very very quiet.
Subsonic .300 Blackout out of a 16" barrel is not very quiet.
How quite would subsonic .300 be out of a 20" barrel if you used a fast burning powder.
The idea is that all the powder is burned up and maybe the bullet is even staring to slow down already before it leaves the barrel.
Why can't I find any info on any loads like this?
Seems like the concept is already proven with the .22lr.
>>27924954
wouldnt slower burning powder make less noise?
>>27924985
no. powder burning *in air* is effectively the same.
The idea OP suggests is that all the powder is burned in the barrel, leaving nothing to burn in the air.
OP is implying that the burning powder makes the supersonic crack.
OP is retarded.
>>27924985
AFIK slow burning powder would still be burning when the bullet exits the muzzle, making a flash and a bang
>>27925067
You could load some cartridges with black powder and experiment.
>>27925067
OP did not imply that, your illiteracy makes you look retarded.
The bang comes from 2 parts, hot gases expanding out of the barrel including unburnt/burning powder (the fireball) and the supersonic crack of the bullet.
So if we have a subsonic bullet the supersonic crack is gone. What I'm saying is that you're comprehension is poor and you are dumb.
>>27925129
had a decent kek reading this
I'm certain if the barrel were long enough this could be done so it was silent without being suppressed.
The question is how long would the barrel have to be?
I don't think you could just burn all the powder up right at primer strike because the pressures on the chamber would be pretty severe.
>>27925129
>you're
God damn it. Look, just because I'm dumb doesn't make you smart.
>>27924954
>Seems like the concept is already proven with the .22lr.
You can get a similar effect with 9mm subsonic loads out of a 16" direct blowback carbine.
>>27925198
Cool thank you.
So I tried to youtube search this and no results, never any results.
>>27925067
The way I read it is that OP is talking about exit bore pressure, which would make a difference the longer the barrel is.
Granted OP, 22lr subsonic is quiet in comparison to normal loadings but it is still around 140db unsuppressed. What I would be interested in finding out is what the exit bore pressure is for that round and compare that to centerfire offerings.
In 556 ar15s a 6" bbl change will have a 1.5db change in sound unsuppressed and will have a 3-6db change when shot suppressed. exit bore pressure in that 6" bbl change will also be about 60-65%.
>>27925256
Thank you anon. I do not have a means of measuring sound out of my gun but can tell you that a Marlin 60 with subsonic ammo, all you hear is the "swoosh" of the bullet with no crack or pop except for the occasional round that breaks the sound barrier which is about 1 in 20 based on my experience.
This guy, >>27925198 say you can do it with a 9mm out of a carbine.
You have posted an understanding and articulate response. Thank you, sincerely.
So, I don't have a .300 blackout but am seriously considering it. I could get a pistol or I could get a rifle length upper. So I was curious about the "exit bore pressure" as you put it for a 20" barrel.
It's hard to believe that nobody seems to have tried it or at least posted a failed effort at trying it.
>>27925361
It takes time and money to test it.
http://www.dtic.mil/ndia/2010armament/WednesdayCumberlandPhilipDater.pdf
>>27925400
Cool link, this graph is exactly what I was asking for just for subsonic .300 instead of m855.
Thanks again.
>>27925501
how is this measured, 1" from bore?
no way in hell there is only ~1dB difference from a pistol barrel and a 24" bolt gun barrel.
>>27925523
>how is this measured, 1" from bore?
It's measured 1" inside the barrel. There are pictures in the link.
>no way in hell there is only ~1dB difference from a pistol barrel and a 24" bolt gun barrel.
1dB = 10 times as loud.
>>27925523
read the article I posted >>27925400 they show the methodology of their testing. and there is about 2.5db total, which is almost double the acoustical energy, but is barely noticeable to the human ear.
http://trace.wisc.edu/docs/2004-About-dB/
>>27925580
The fuck? So 100db is 500 times louder than 50db?
>>27925634
I dunno man, I'm a pseudo science kind of guy.
>How quite would subsonic .300 be out of a 20" barrel if you used a fast burning powder.
Not very.
Powder burning outside the barrel isn't what's responsible for the majority of the sound; it's the sudden release of pressure as the bullet exits the crown. .22 LR (especially subsonic) is not very high pressure, but .300 Blackout is.
>>27925672
What if you got to the point by design that the bullet reached top speed say a third or halfway down the barrel. Would that equate to cutting the pressure in half?
>>27925580
>1dB = 10 times as loud.
No, 10 dB = 10 times the intensity. 20 dB = 100 times the intensity.
Don't ask me why. It seems unnecessarily complicated to me but it is what it is.
>>27925634
100 dB is about 1.6 times more intense than 50 dB (assuming I didn't fuck up).
>>27925703
>100 dB is 1.6 times more intense than 50dB
How do you figure?
50=10log(x1/x2)
5=log(x1/x2)
(x1/x2)=100000
A difference of 50 dB corresponds to a factor of 100000.
>>27925695
Yes, but the bullet would now be slow as fuck.
>>27924954
Depends on if you need it to cycle a semi-auto rifle.
The same .30cal subsonic load for single shot or bolt-action rifles has been pretty much consistent for the last 30 years, be they .308win, .303brit, .300 savage, .30TC, or .300blk.
>2.5-3.5gr Red Dot
>magnum rifle primer
>heavy bullet
Even without a suppressor, this load through a 24" bolt-action .308 is almost silent.
Why?
Red Dot is one of the fastest shotgun powders made. Shotgun powders are also used in modern-autoloading pistol loads (9x19, etc), or are at least of a similar burn speed (most shotgun powders are large flake powders that take up a lot of case volume, which is why they're used in subsonic rifle loads as it prevents detonation from too-low powder fill volume). As a result of being a super fast powder, it burns it all in the first 3-4" of barrel and the gaseous byproduct of the combustion (what actually pushes the bullet) has lost almost all of its pressure and most of its heat by the time the projectile exits a 10" or longer barrel. The longer the barrel, the closer to atmospheric norm the gases are.
Fun fact: H110/W296, the premier/most-used powder for both super and sub .300blk, was originally designed as a .410 and 28ga shotgun powder. Same with 2400 and VV110.
>>27926035
>>27925703
Engineeranon here.
Decibels work on a log-base-10 system.
Decibels in sound is represented by the equation DELTAdB = 10*log-sub-10(Intensity/base intensity) where base intensity is usually defined as the minimum sound intensity required for human hearing.
The ratio (Intensity/Base) is the important part for determining CHANGES in decibel. To find true loudness, you need to use the minimum intensity I previously mentioned. It's defined based on the pressure of a controlled room at 1 atm, and other constants, but I don't really ever use the base value.
If the current intensity is equal to the base intensity, you have 10log(1) = 0, i.e. the change in decibels is zero.
If the intensity is 10 times the base intensity, you have 10log(10) = 10*1 = 10 dB increase.
If the intensity is 10 times less than the base, you have 10log(0.1) = -10log(10) = -10 dB = 10 dB decrease.
Thus, every increase in 10 dB represents a multiple of 10 times the base intensity. 20dB = 100 times, 30 = 1000 times, etc.
Of similar note is the Richter scale for earthquake intensity, which also uses a log-10 system. A 9.0 earthquake is 10 times stronger than an 8.0 earthquake.
Logs just work really well for defining intensity and power transfer.
>>27925634
yup. dB is a log scale, where the X dB is actually 10^X. Other uses of a log scale is earthquake power, the Richter scale. So if an earthquake is a 5 on the Richter scale, a 6 is 10 times more powerful.
Science does this because there lazy fucks. They don't want to write 10,000,000,000 so they'll call it 10 dB.
>>27926120
Can confirm. This standard load is older than dirt.
I personally use variations of it for .30 Herrett and 7mm TCU to fuck around with and plink cheaply with my Contender.
>for .30 Herrett it's 1.9gr Red Dot, standard LR primer, and 245gr cast NOE bullet
>for 7mm TCU it's 1.7gr Red Dot, SRM primer (all I have since I load a shitload of 5.56), and 176gr Lyman heavy-silhouette cast.
Both are shot through a 14" barrel.
Both drop like a rock but are extremely accurate. Drop is something like 7" @ 100 over a 50yd zero but off bags I can print 1" groups all day long. I've not chronographed the 7TCU but the .30 Herrett has a MV of only 580fps. Definitely don't wanna try killing anything with either, but at <$0.04/rd it's cheap and challenging fun.
>the other benefit is the chamber pressure is so low I don't have to resize or trim brass afterwards
>>27926139
>>27926268
Awesome! wonder how far you could crank that up without the bang.
>>27924954
>Anonymous 11/19/15(Thu)13:15:44 No.27928080
i need my shit to be silent so i can kill niggers during zombie apoc and not get killed by zombies
>>27924954
Just asking about the speakers you posted.
What kinds of sound quality do you get?
>>27930258
Not OP. But that looks like a well defined box for midrange sound. Bose made their name off of well designed boxes like this but with shit drivers.
Amir Bose was once quoted as saying his drivers cost 65 cents to manufacture.
>>27930258
>>27930878
OP here, cool to see thread still up.
I do not have those speaker boxes but basically this >>27930878
I'm thinking of buying some cheap bluetooth speakers like what they sell for phones and cannibalizing it into some homemade speaker boxes like shown in the OP. It's basically just a trumpet for the speaker.
Haven't decided yet if worth the trouble and frankly just thought it was a good picture for the thread topic.
Figured this thread would be mostly people calling me stupid but
>>27926268
>>27926120
>>27925256
>>27925400
were really helpful. Thank you again.
>>27930878
Cool. I have two tower speakers from Polk that have since been discontinued from production, ca 1995. Fucking amazing sound, but take a lot of juice.
>>27932867
Polk makes some of the best sounding speakers I have ever heard.
>>27932877
No shit. My surround setup includes those two in the front, a center speaker, and two "bookshelf" speakers that I mounted to the wall.
The receiver is rated to 5.2 surround, and I can give it more juice than I dare to fuck my hearing. It's a pity that more of the old style drivers and towers aren't more common.
>>27931290
>>27932867
>>27932877
>>27932915
Buy some decent drivers then build your box.
They still do make drivers like the old style theyre just expensive. Dont buy polks under $200 either they arent very good.
>>27931290
do old people still buy those things and think they're the shit?
>>27924985
No, fast powders are quietest, the explosion happens faster while the bullet is in the barrel amd burn completely, so the gas isn't expanding as much.
This is why people use very fast pistol powders for suppressed 9mm, the ammount of the fast powder is lower, and the max power is lower, but that doesnt matter as you cant exceed 1050 fps anyway to avoid supersonic crack.
>>27926120
God damnit, not this again. Now I have to avoid the temptation to get a 7.62x54r lee loader and have a bit of fun, as I have 1000 large magnum rifle primers that I have no use for, bullseye (supposedly similar to red dot so I could find a load for it) and trailboss powders, and could load with either pulled surplus bullets or the 90 grain XTP bullets that I load for my TT33.
>>27935051
>90 grain boolit
>in a 7.62x54
Damn man, you could probably hit 3250fps with the right powder, maybe even push 3500fps.
One of these days I'll get some ~100gr .30 cal mold and some antimony and see how fast I can push a powder coated boolit.
>>27935171
I'd be more tempted to get some of those plastic sabots and try loading tungsten carbide rods into them. Only problem would be shaping the tungsten carbide rods into nice ~55 grain pointed pieces.
>>27935171
>>27935221
Forgot, I also have some 0 buckshot that I use for cheap plinking loads for my Nagant revolver, but those would probably come apart if I tried to shoot them to fast.
>>27935287
Nice. I read about revolutionaries in some euro or slav country using buckshot in Mosins for a quiet insurrection.
Can't find the story now, but I think it involved some surprisingly familiar powder.
>>27935381
Never heard about buckshot, I've heard of pistol bullets being used for that purpose though which is why I originally mentioned the 90 grain XTP.
