Suppressor Engineering 101

Yes, it can be legal to make a silencer. For everything Form-1, from silencer designs that are easily made, to filing forms with the BATF, to 3D modeling. Remember, you must have an approved BATF Form-1 to make a silencer. All NFA laws apply.

Moderators: mpallett, bakerjw

User avatar
Bowen1911
Silent But Deadly
Posts: 1644
Joined: Mon Jan 25, 2010 3:31 pm
Location: Idaho

Re: Suppressor Engineering 101

Post by Bowen1911 »

wolf wrote:Eureka :wink:

Archimedes

This exclamation is most famously attributed to the ancient Greek scholar Archimedes; he reportedly proclaimed "Eureka!" when he stepped into a bath and noticed that the water level rose — he suddenly understood that the volume of water displaced must be equal to the volume of the part of his body he had submerged. This meant that the volume of irregular objects could be measured with precision, :wink:

Do elaborate sir...



I'm kidding.
I just use the estimate of a cylinder that size, but displacement would be pretty dang precise.
"I notice that everybody that is pro-abortion already has been born."
--Ronald Reagan

Form 1 .22 can
http://www.youtube.com/watch?v=mq-XG3tn7s0
User avatar
LavaRed
Silent But Deadly
Posts: 1830
Joined: Sun Apr 05, 2009 7:11 pm
Location: CA

Re: Suppressor Engineering 101

Post by LavaRed »

Bowen1911 wrote:
wolf wrote:Eureka :wink:

Archimedes

This exclamation is most famously attributed to the ancient Greek scholar Archimedes; he reportedly proclaimed "Eureka!" when he stepped into a bath and noticed that the water level rose — he suddenly understood that the volume of water displaced must be equal to the volume of the part of his body he had submerged. This meant that the volume of irregular objects could be measured with precision, :wink:

Do elaborate sir...



I'm kidding.
I just use the estimate of a cylinder that size, but displacement would be pretty dang precise.
Fill brass case with water, empty all the water into probe tube or other volume-measuring device.
"There are no stupid questions, only stupid people". -MAJ MALFUNCTION
User avatar
wolf
Silent But Deadly
Posts: 2591
Joined: Wed Nov 22, 2006 10:32 am

Re: Suppressor Engineering 101

Post by wolf »

LavaRed wrote:
Bowen1911 wrote:
wolf wrote:Eureka :wink:

Archimedes

This exclamation is most famously attributed to the ancient Greek scholar Archimedes; he reportedly proclaimed "Eureka!" when he stepped into a bath and noticed that the water level rose — he suddenly understood that the volume of water displaced must be equal to the volume of the part of his body he had submerged. This meant that the volume of irregular objects could be measured with precision, :wink:

Do elaborate sir...



I'm kidding.
I just use the estimate of a cylinder that size, but displacement would be pretty dang precise.
Fill brass case with water, empty all the water into probe tube or other volume-measuring device.
And he then would know the internal volume of the case :wink:
but he want to know the volume of the chamber


To the op ,, why i have to ask , do you need the volume of the chamber :?:
User avatar
Droopy Almond
New Member
Posts: 1
Joined: Tue Jan 04, 2011 10:51 pm
Location: Missouri

Re: Suppressor Engineering 101

Post by Droopy Almond »

New to the forum so sorry if this is dredging up a dead post but this is a good post, interesting subject and I thought I'd throw my $0.02 in...
Bowen1911 wrote:este, looking in my strength of materials book, the tensile stress from the hoop stress doesn't increase linearly with relation to the wall thickness for cylinders.

hoop stress= pressure* inner radius^2/(outer radius^2-inner radius^2) * (1+outer radius^2/inner radius^2)

granted it is near linear due to it being thin walled. ----- hoop stress = pressure* average radius/ thickness

the difference in radius is less than 10 percent, so the book says to use the thin walled formula.
Sounds good but (I might be preaching to the choir) imo if there is ever a question about which eqn to use (especially at dangerous psi), always use the thick walled eqn as opposed to the thin. The thin walled eqn makes assumptions while the thick does not. Better safe than sorry. This can also be handy during the design stage when dimensions are not yet set in stone.

Droopy Almond
You were supposed to be this colossus, you were this great legendary thing, and yet he gains!!
User avatar
James DeGroat
Elite Industry Professional
Posts: 988
Joined: Mon Apr 25, 2005 6:27 pm
Location: New Mexico
Contact:

Re: Suppressor Engineering 101

Post by James DeGroat »

Very nice post Mongo
James DeGroat
President
DeGroat Tactical Armaments, LLC.
www.ArmamentSales.com

Specializing in the 7.62mm Minigun, Suppressors, and NFA Weapons/Accessories (including Artillery and Flame Throwers).
User avatar
Mongo
Silent But Deadly
Posts: 4168
Joined: Fri May 20, 2005 12:27 pm
Location: Texas
Contact:

Re: Suppressor Engineering 101

Post by Mongo »

bump for people that have questions
Firearms Engineer for hire on piece work basis.
No job is too expensive :)
http://weaponblueprints.com/
User avatar
DTdr2
New Member
Posts: 7
Joined: Sat Mar 19, 2011 2:41 pm
Location: Somewhere in Texas

Re: Suppressor Engineering 101

Post by DTdr2 »

Great work, and even better that it's from a Red Raider....
Please keep it going
User avatar
kdiver58
Elite Member
Posts: 199
Joined: Wed May 28, 2008 5:29 pm
Location: Alpharetta, GA

Re: Suppressor Engineering 101

Post by kdiver58 »

This needs to be a sticky !!!
fdv99
Member
Posts: 10
Joined: Wed Dec 30, 2009 8:02 am
Location: south

Re: Suppressor Engineering 101

Post by fdv99 »

I started doing calculations for a .223 Ar-15 suppressor yesterday and ended up with 21,000 PSI entering the suppressor. That is with a safety factor of 1.5. My question is, is that value about right, or too low?

Also, I am doing flow simulations in solidworks, which i know are not that accurate, but was wondering what input temperatures to put. I currently put 21,000 psi and 200 degrees F for input and atmosphere pressure and 100 degrees F out. Any ideas as to the pressure out and the temps i would be dealing with?

Thanks for the great thread and all the help.
SRM
Silent But Deadly
Posts: 1825
Joined: Mon Mar 15, 2010 7:20 pm
Location: wyoming

Re: Suppressor Engineering 101

Post by SRM »

bump.
:D
maxxwell86
Member
Posts: 27
Joined: Mon Aug 23, 2010 11:52 pm

Re: Suppressor Engineering 101

Post by maxxwell86 »

Has anyone ever seen a comparison study on how different loads affect frp? After reading this thread and Paul's thread on frp I got to thinking (always a dangerous proposition).

Someone already probably had this idea but I was thinking that, just as you can adjust blast baffle distance to change frp, form 1 builders might be able to reverse engineer a load to work with the baffle distance they are stuck with in their one time only build if they had some useful data.

Conversely, if anyone has already made a basic study of the relationship between muzzle pressure and blast baffle distance, it might give a better starting point for design.

I'm sure that some of the commercial makers have done it with flow simulations, and the research would have to be expensive due to the various types of baffle designs and calibers. Probably considered trade secrets.
Historian
Silent But Deadly
Posts: 3503
Joined: Mon Mar 29, 2010 10:37 pm

Re: Suppressor Engineering 101

Post by Historian »

maxxwell86 wrote:Has anyone ever seen a comparison study on how different loads affect frp? After reading this thread and Paul's thread on frp I got to thinking (always a dangerous proposition).

Someone already probably had this idea but I was thinking that, just as you can adjust blast baffle distance to change frp, form 1 builders might be able to reverse engineer a load to work with the baffle distance they are stuck with in their one time only build if they had some useful data.

Conversely, if anyone has already made a basic study of the relationship between muzzle pressure and blast baffle distance, it might give a better starting point for design.

I'm sure that some of the commercial makers have done it with flow simulations, and the research would have to be expensive due to the various types of baffle designs and calibers. Probably considered trade secrets.
You do raise an interesting idea. How difficult would it be for a can maker to have the first baffle threaded
so that the user could screw it in or out to tune it ... like the old carbs ... for performance.

Congratulations.
maxxwell86
Member
Posts: 27
Joined: Mon Aug 23, 2010 11:52 pm

Re: Suppressor Engineering 101

Post by maxxwell86 »

You do raise an interesting idea. How difficult would it be for a can maker to have the first baffle threaded
so that the user could screw it in or out to tune it ... like the old carbs ... for performance.
Threaded blast baffle...now that's an idea! :D Solves the whole form 1 issue of "ya can't change it once it's done".

Maybe thread the entire tube and make all the baffles adjustable? One the other hand, maybe not. We'd have to have someone open a shop to correct all the problems we created by adjusting them. :lol:
User avatar
twodollarbill
Silent But Deadly
Posts: 420
Joined: Wed May 30, 2007 5:25 pm
Location: wisconsin

Re: Suppressor Engineering 101

Post by twodollarbill »

I would think you would have to have it mounted in a module or something
so that you could adjust it's spacing and not disturb the rest of the stack.
If it was just inside the threaded tube, it would take awhile until the carbon buildup held it.
Back in the day when we could play and changed things around. I recall my first .22 lr can had
a 1" blast spacer, 1/2" spacers between the baffles and a 3/4" exit spacer.
I played around with the placement of those and found the 1/2" blast spacer gave the best results with frp.
maxxwell86
Member
Posts: 27
Joined: Mon Aug 23, 2010 11:52 pm

Re: Suppressor Engineering 101

Post by maxxwell86 »

Maybe if we all built with a series of 1/2" spacers (and maybe a 1/4 & 3/4 thrown in for good measure) between all the baffles we could adjust the internals and not mess with threading the blast baffle.

There are multiple blast chamber suppressors as well as logarithmic baffle layouts out there so it must be useful in some cases.

Just swap the order of the parts around, no new parts added just re-oriented. No ATF violation, better performance.

True modularity and load/platform adjustable. A few more parting cuts on the lathe but well worth the effort.
Post Reply