muzzle pressure /hoop strength worksheet ?

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partsguy22
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muzzle pressure /hoop strength worksheet ?

Post by partsguy22 » Tue Mar 03, 2015 9:52 pm

A few weeks ago I found a .xls worksheet with this stuff. You input chamber pressure, bore ,barrel length ,tube thickness ect

The problem is I cant find it now ,any ideas?

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Re: muzzle pressure /hoop strength worksheet ?

Post by toytraindoc » Thu Mar 05, 2015 1:51 pm

Google silencer back pressure calculator. That might be the one you are looking for.
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Re: muzzle pressure /hoop strength worksheet ?

Post by Bendersquint » Thu Mar 05, 2015 2:50 pm

toytraindoc wrote:Google silencer back pressure calculator. That might be the one you are looking for.
He is looking for the FIREARM silencer caluculator, not the industrial one that has nothing to do with firearms.

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Re: muzzle pressure /hoop strength worksheet ?

Post by partsguy22 » Thu Mar 05, 2015 4:13 pm

Thanks but that's not the one I thought I found. I'm starting to think i just imagined it all .

I finally found all the formulas last night to figure it out .

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Re: muzzle pressure /hoop strength worksheet ?

Post by Bendersquint » Thu Mar 05, 2015 4:16 pm

partsguy22 wrote:Thanks but that's not the one I thought I found. I'm starting to think i just imagined it all .

I finally found all the formulas last night to figure it out .
Unfortunately I think you probably did imagine that.

If it were out there it would be posted in here and lots of people would have a copy of it.

Closest thing I can think of is QuickLoads for providing some of that information.

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Re: muzzle pressure /hoop strength worksheet ?

Post by partsguy22 » Thu Mar 05, 2015 6:21 pm

I'm not nuts :D I found It.
https://docs.google.com/spreadsheets/d/ ... sp=sharing
It looks like it was originally posted on ar15.com

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Re: muzzle pressure /hoop strength worksheet ?

Post by Bendersquint » Thu Mar 05, 2015 6:43 pm

partsguy22 wrote:I'm not nuts :D I found It.
https://docs.google.com/spreadsheets/d/ ... sp=sharing
It looks like it was originally posted on ar15.com
Neat, gonna have to verify the formulas and all before would trust it though.

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Re: muzzle pressure /hoop strength worksheet ?

Post by partsguy22 » Thu Mar 05, 2015 6:54 pm

I checked the muzzle pressure part against the " EFFECTS OF BARREL LENGTH ON BORE PRESSURE, PROJECTILE VELOCITY and SOUND MEASUREMENT ".PDF by Philip Dater and they seem to agree

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Re: muzzle pressure /hoop strength worksheet ?

Post by FarmDadCO » Thu Mar 05, 2015 7:26 pm

Fantastic! Thanks for digging this up !

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Re: muzzle pressure /hoop strength worksheet ?

Post by Bendersquint » Thu Mar 05, 2015 7:52 pm

Someone screwed with the file, its now giving me results saying my muzzle pressure is around 50K PSI.

Means the chamber pressure is well over 350K psi.

Impossible.

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Re: muzzle pressure /hoop strength worksheet ?

Post by FarmDadCO » Thu Mar 05, 2015 8:06 pm

Bender Try this

http://www35.zippyshare.com/v/18kTjNxu/file.html


I upped the copy i had saved immediately on seeing it .

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Re: muzzle pressure /hoop strength worksheet ?

Post by Bendersquint » Thu Mar 05, 2015 8:11 pm

FarmDadCO wrote:Bender Try this

http://www35.zippyshare.com/v/18kTjNxu/file.html


I upped the copy i had saved immediately on seeing it .
Thanks!

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Re: muzzle pressure /hoop strength worksheet ?

Post by BlwnGazkit » Thu Mar 05, 2015 8:40 pm

It's my spreadsheet I made when working on my design a few months ago.

A few people asked to see it so I uploaded it to google docs.

I'd be interested to know if I screwed up somewhere... Also, there's no error checking in there. If you put an incorrect value in, the answers will be odd.

ie. Someone was trying a case volume of 25ci (I probably wasn't clear on the form, but case volume should be entered in cubic inches) for a .223 cartridge. Going on memory, a .223 case is something like 0.113 or 0.114 cubic inches.
Last edited by BlwnGazkit on Fri Mar 06, 2015 4:17 pm, edited 1 time in total.

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Re: muzzle pressure /hoop strength worksheet ?

Post by FarmDadCO » Thu Mar 05, 2015 9:08 pm

BlwnGazkit Thanks for sharing this with everyone .

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Re: muzzle pressure /hoop strength worksheet ?

Post by partsguy22 » Thu Mar 05, 2015 9:53 pm

To get it to jive with the dater doc. I think I used .0985ci and 62,000 psi for 5.56 as per the report

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Re: muzzle pressure /hoop strength worksheet ?

Post by BlwnGazkit » Thu Mar 05, 2015 10:16 pm

partsguy22 wrote:To get it to jive with the dater doc. I think I used .0985ci and 62,000 psi for 5.56 as per the report

Just checked my form against the Dater doc.

Chamber Pressure of M855 (used in Dater tests) is 55,000psi, case volume is 1.85ml or 0.112ci. My form spits out muzzle pressures within a few hundred PSI, with the margin of error decreasing as the barrel length decreases; so I'd call that close enough after allowing for variances. Bear in mind Dater's results are the averages of several shots and his own tests showed as much as a 1,100psi variation.

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Re: muzzle pressure /hoop strength worksheet ?

Post by partsguy22 » Thu Mar 05, 2015 11:46 pm

OK that makes sense, the way I read it was 55kpsi was at 3" not chamber pressure .
I thought M855 was 62kpsi and sammi spec. .223 was 55kpsi ,but it seems that mixup is from different test methods (c.i.p. vs sammi)

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Re: muzzle pressure /hoop strength worksheet ?

Post by Meche_03 » Fri Mar 06, 2015 2:37 am

partsguy22 wrote:OK that makes sense, the way I read it was 55kpsi was at 3" not chamber pressure .
I thought M855 was 62kpsi and sammi spec. .223 was 55kpsi ,but it seems that mixup is from different test methods (c.i.p. vs sammi)
M855 is a 5.56 spec not .223 and M855 is pushing beyond 5.56 spec to proofing load pressure. Its the main reason why one should not fire 5.56 in 223. Higher pressure and slight case difference can cause huge pressure spike.

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Re: muzzle pressure /hoop strength worksheet ?

Post by BlwnGazkit » Fri Mar 06, 2015 10:48 am

Meche_03 wrote: M855 is a 5.56 spec not .223 and M855 is pushing beyond 5.56 spec to proofing load pressure. Its the main reason why one should not fire 5.56 in 223. Higher pressure and slight case difference can cause huge pressure spike.

That's incorrect.

http://en.wikipedia.org/wiki/5.56%C3%97 ... _Remington


Notice 5.56 & commercial .223 both have the same max chamber pressure IF using the same test standard.

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Re: muzzle pressure /hoop strength worksheet ?

Post by RavenArmament » Sat Mar 07, 2015 6:51 am

The result fields don't display for me.
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Re: muzzle pressure /hoop strength worksheet ?

Post by Meche_03 » Sun Mar 08, 2015 2:11 am

BlwnGazkit wrote:
Meche_03 wrote: M855 is a 5.56 spec not .223 and M855 is pushing beyond 5.56 spec to proofing load pressure. Its the main reason why one should not fire 5.56 in 223. Higher pressure and slight case difference can cause huge pressure spike.

That's incorrect.

http://en.wikipedia.org/wiki/5.56%C3%97 ... _Remington


Notice 5.56 & commercial .223 both have the same max chamber pressure IF using the same test standard.
I was a bit confused and wiki is a bit wrong. I was partially recalling the possible problem with firing 5.56 in 223 chamber. 5.56 fired in tight 223 chamber can spike pressure up an additional 6ksi.

The cases are not the same for 223 and 5.56. They can be the same but the dimensional tolerances have different reference planes for some dimensions. That results in possible case dimensions being different if i recall. It should not change peak pressures in rounds fired in matching spec chambers.

Now I agree that 55 grain NATO ball round had a max pressure of 55ksi and a maximum pressure of 61ksi. This is the same spec for m855.

I was misremembering m855a1 pressures. But I don't recall the actual spec being released to the public, it has been industry rumer. The Army has released PowerPoint slides stating the a1 pressures are higher than normal m855.

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Re: muzzle pressure /hoop strength worksheet ?

Post by colimr » Fri Mar 13, 2015 3:58 pm

With a gas operated system where a portion of pressure is used to cycle the bolt.How do you figure the muzzle pressure?In a bolt action, the pressure must be a singular calculation because from ignition to exit there is no port for pressure loss, but how do you figure the pressure in a gas operated system? Is there a second calculation or is it so small that it is covered by the selection of the safety factor?There has to be a drop in muzzle pressure as the bullet moves down the barrel and passes the gas port.Am I correct or is muzzle pressure in a bolt action and a gas operated system the same? Ive read here that many of you use one suppressor on multiple calibers and firearms but no one ever mentions one firearm having more or less pressure just the concerne for bore size.

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Re: muzzle pressure /hoop strength worksheet ?

Post by Meche_03 » Fri Mar 13, 2015 10:19 pm

The muzzle pressure should be slightly different between the two operating systems, but I don't believe it is significant enough to worry about. If you assume a bolt action type setup it will give you the higher pressure of the two systems and thus result in a bit of a conservative build on a gas driven system.

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Re: muzzle pressure /hoop strength worksheet ?

Post by cdhknives » Sun Mar 15, 2015 2:23 pm

WARNING! MY ANTIVIRUS WENT NUTS WHEN I TRIED THE ZIPPYSHARE SITE LINK ON THIS THREAD! USE WITH CAUTION!
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Re: muzzle pressure /hoop strength worksheet ?

Post by yondering » Tue Mar 17, 2015 11:38 pm

FarmDadCO wrote:Bender Try this

http://www35.zippyshare.com/v/18kTjNxu/file.html


I upped the copy i had saved immediately on seeing it .
This one worked for me the other day, no antivirus issues.

It looks like the hoop stress calculation is incorrect though; it doesn't account for the tube wall thickness. This calculator also doesn't account for volume of the gas in the stress calculations, using only muzzle pressure as a singular number.

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