7mm Allen Mag test rifle finished.....

[davewilson]

Re: wc872 burn rate

group sizes are harder to measure when bullets are making full profile holes but it would be easier to cut the star out of the paper at the carnival. i know logic is not on my side,but i think a 9 will put it to sleep. please get that thing out and burn some "COOL BURNING" wc872 or whatever it is!

 

[ss7mm]

Re. 7mm Allen Mag test rifle finished.....

I don't have any of the 175 grain Wildcats, but do have the 169.5 and 200's for comparison.

This is the 200 Wildcat, 160 Accubond, 169.5 Wildcat and 200 Wildcat with top of boat tails even.

This is the 200 Wildcat, 160 Accubond, 169.5 Wildcat and 200 Wildcat with bases even for OAL comparison.

 

[ricka0]

Re: wc872 burn rate

Powders are not differentiated by the gases they create - as the text states they are differentiate by burn rates. The mechanism that propels the bullet is heat - nothing you quote obviates that fact.

Find a reference supporting your assertion, that a gun is not a simple heat pump.

 

[ricka0]

Re: wc872 burn rate

[ QUOTE ]
[ QUOTE ]
According to the chemists I've talked to, (and previously posted) there is <font color=" green"> virtually no phase changes </font> going on or creation of new gas molecules. (If you can cite a credible reference stating otherwise I'd love to see it.)

[/ QUOTE ]
I guess I drink way too much beer when I reload. I simply have no memory of ever filling a case with a compressed gas. Is that sort of like putting air in the tires of your truck? Or filling a propane tank (hey even that one has a phase change too!)?

Sorry, but I don't need to cite "sources" to tell me what I'm dropping in the case is a lot of small chunks of a solid. And what comes out of the barrel is mainly gas. And that there's a burning process in between responsible for the change which creates a large portion of the heat the barrel [sic] recieves.
Your whole PV=nRT model would likely work well for a Daisy air rifle.

[/ QUOTE ]

PV=nRT is not my model - but thanks for crediting me with it You are getting closer. Yes what heats the barrel is what pushes the bullet. Not the creation of gases or trival phase change.

What % contribution to bullet acceleration is heat?

 

[ricka0]

Re: wc872 burn rate

[ QUOTE ]
BigBore,
Some more info for your info.

http://www.fas.org/man/dod-101/navy/docs/fun/part16.htm



The above info talks pretty clearly about gas production.

I didn't notice before that you said the holy grail of a pressure curve would be constant (flat until the bullet exits the muzzle).
That is the first thing dealt with in Gun Propulsion Technology in the section about how propellant is designed.
They say that naively considering that the velocity is given by the integral of the pressure curve, and that the gun can withstand only a certain max pressure one might think that a flat pressure curve is desirable. In fact it is not, and they explain why.
If you are really interested in these things you should really read that book.

[/ QUOTE ]

I'm afraid your citation clearly points out what I meant by credible (it clearly demonstrates no credibility and numerous errors). The citation makes no mention of heat. How much do you feel heat contributes to the acceleration of the bullet?

Here are the reasons he sites why a flat curve is undesirable (flat curve at max pressure) <ul type="square"> [*]producing excessive erosion (which would materially decrease the accurate life of the gun) [*]brilliant flashes [*]non-uniform velocities due to high muzzle pressure would result [/list]
Only his first reason is accurate. Yes, a 300 RUM loaded to capacity does burn out a barrel faster than a .308 My 300 RUMs (and the Allen Uber Mags) outperform a 308 primarily because they have a much flatter curve - a 308 max pressure is not much lower than my 300 RUM. Performance is differentiated by the area under the curve.

[ QUOTE ]
brilliant flashes

[/ QUOTE ] - some truth to this, but not a reason to avoid higher velocity in a BR or hunting gun. Important if you are a sniper. Much more important in flash is how much unburnt powder you have when the bullet exits.

[ QUOTE ]
non-uniform velocities due to high muzzle pressure

[/ QUOTE ] -- Perhaps a hint of truth to this. 300 RUMS and Allen uber mags are probably not the best choice for point blank BR competition. A slow .308 is likely easier to get ultra consistent.
His statement [ QUOTE ]
due to high muzzle pressure

[/ QUOTE ] contradicts his entire premise of a flat curve. You can get more acceleration with lower pressure with a flat pressure curve.

The amateur work you cite incorrectly writes: Work = KE = 1mv2, if the Initial Velocity is zero.
I don't often shoot my guns while running &amp;#61514;
[ QUOTE ]
<font color="purple"> If you are really interested in these things you should really read that book. </font>

[/ QUOTE ]
No thanks. I'll stick to science. The ref is clearly not science.
[ QUOTE ]
<font color="purple"> Note: Often the pressure-travel curve is the given variable, and the gun tube thickness is then dictated by the pressure-travel curve. </font>

[/ QUOTE ]

He has clearly never spoken to our pal SAMMI.

Please answer the questions: <ul type="square"> [*]What % of bullet acceleration is determined by heat [*]Can you provide any reference that shows different powders differ significantly in bullet acceleration mechanism (ie one uses heat, the other uses increase in n) [*]Why does a 300 RUM significantly outperform a .308 given the same length barrel and reloaded to the same max pressure? [/list]

 

[ricka0]

[ QUOTE ]
BigBore, <font color="purple">
What do you think of the references I list below?</font>

[/ QUOTE ]

They appear to be credible (peer reviewed) - unlike your other ref. No where do they say rifle powders differ significantly in creation of new gases. They corroborate my assertion.
Find something that supports your assertion - that different powders producing the same velocity transfer their chemical energy to KE by heat in one case and another mechanism for the other. You can't because gun powder uses heat to accelerate the bullet.

 

[ricka0]

Re: wc872 burn rate

[ QUOTE ]
Your whole PV=nRT model would likely work well for a Daisy air rifle.

[/ QUOTE ]

Yes it does, almost entirely by increasing n (for a pump daisy). I think most air rifles are spring powered, in which case PV=nRT is not applicable. But I can show you how to integrate a spring (not exceeding hookes law) to get the KE. The integration is trivial.

 

[Jon A]

Re: wc872 burn rate

[ QUOTE ]
Find a reference supporting your assertion, that a gun is not a simple heat pump.

[/ QUOTE ]
My only assertion is that your assertion is incorrect. You're the one that made the wild claim:

If Kirby loads his rifle to max peak pressure with two different powders, both loads will heat the barrel exactly the same amount, no matter what. Any difference could only be attributed to magic.

While asking everybody else for references, you've failed to give a single one of your own--besides "some chemists I know"--to support your wild claim.

Really, are you a Freshman College student or something? You certainly sound like one. Have you actually completed Thermo I and II, Heat Transfer I and II, Physics I, II, III, etc, etc, etc, yada, yada, yada?

From your posts, I highly doubt you have. Your mis-application of laws and misunderstandings at the most basic fundamental levels are bordering upon comical.

 

[Fiftydriver]

Re: wc872 burn rate

Alright, now things are getting a bit out of hand discussing powders. Anyone what to actually get back to talking about bullets, barrels and ballistics????? /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif

Points taken by all, lets drop it before things get flaming more then they are.

Thanks,

Kirby Allen(50)

 

[Richard338]

Re: wc872 burn rate

BigBore,
Please read this one post carefully. I will explain from my perspective why you are wrong, and why you owe myself and others an apology. I will not be your new Dan Hackett, so if you don't get where I'm coming from after this, then we can just agree that we can't comunicate.

My summary:
1) People posted observations about hotter/cooler burning powders.
2) You said they are wrong, and it is all "hi-skoul" chemistry.
3) I commented that a burning powder charge is a complex, high-temperature/pressure, non-equilibrium system.
4) You dismiss this by saying "it is neither"
etc etc

Any chemist would call a mixture of more than 6 reacting gasses complex (fact). A reaction occuring at 1000's of degrees and up to 50000 psi is high temp/pressure (fact). These accompanied by a rapidly changing reaction chamber would be non-equilibrium (fact).

You tell me to provide credible references for my points, while you simply state yours. Then you apologize that your explanations aren't always clear because you are used to talking to educated people. This is insulting, and arrogant. Even if you were right it is very condescending.

You have some major misconceptions about the phenomena here.
The idea that the purpose of a propellant is to produce gasses is very basic. A byproduct of the reactions is also heat. This heat further increases the reaction rate and pressure. I think most people on this board know this. To try to clear up what you don't understand, I have asked you:
1) state clearly what YOU think is happening.
2) Tell me who the chemists are who you have missunderstood.

As far as the references you can forget all but one.
Gun Propulsion Technology (progress in aeronautics and astronautics). I only gave the one you criticized because it has web access for all. I don't know what journals etc you can access.

You dismiss this saying "I'll stick to science thanks!!?"
That book is the most authoritative on this subject!

The reason I feel you should apologize is not because you are wrong (anyone can be wrong), but because of your insulting way of telling everyone how "well educated" you are.
When I comment on a topic I try to give a simple bottom line. I don't pull out my resume and tell people I'll try to dumb it down for them. You try to mention functions, and tell people you can help them integrate things.

It is very much like someone with only a Masters degree to a) tell everyone about their degree, and b) be wrong. You come off as a real assballs, while not impressing me in the least.

 

[ricka0]

Re: wc872 burn rate

Your facts are in fact wrong - but that is moot and has nothing to do with the issue. Here is the question: What drives a bullet <ul type="square"> [*]Heat contribution [*]n (increase in gas molecules) [*]Yet unidentified mystery force [/list]

The primary force is from heat. different powders producing the same vel Have very similar combustion products - so that portion KE that doesn't derive from heat ( n or the mystery force ) can be condered the same.

All your credible references support my claim. Please answer my questions and support your claim, ie that <font color="red"> two appropriate powders can produce the same Vel - one via heat and the other via n (or the mystery force)</font>
<font color="purple"> [ QUOTE ]

You dismiss this saying "I'll stick to science thanks!!?"
That book is the most authoritative on this subject!


[/ QUOTE ] </font>
All those errors I pointed out and it's the most authoritative? <font color="purple"> [ QUOTE ]
Note: Often the pressure-travel curve is the given variable, and the gun tube thickness is then dictated by the pressure-travel curve.

[/ QUOTE ] </font>
Who designs guns like that? Please answer my questions. Thanks for providing the credible refs that support my claim.
That's it for me unless you can provide a credible reference to your claim. Please answer the questions.

 

[ricka0]

Re: wc872 burn rate

Maybe this can settle the debate. I've emailed my PhD chemist pal with the following experiment design.

Find loads in my 300 RUM producing the same Vel using H50-BMG and wc872. Attach a thermocouple and a RSI pressure Trace. If the velocities are the same, the area under the curve must be the same (do we agree on that)? Measure the temp.

I will have to find a load that burns all the powder of the H50BMG - or the results will be bogus - as the H50BMG remaining after bullet exit simply heats the barrel and does not contribute measurably to acceleration (contrary to your favorite author).

The chemist will probably find flaws with my experiment, as he did with my Ammonia dissolving copper experiment. The biggest problem I see is too much powder.

 

[Richard338]

Re: wc872 burn rate

All of a sudden you are talking about combustion products? What do you think I've been telling you! New molecules? Similar formulations?
You are changing your story as you realize that I'm correct. You were originally saying that no new molecules were formed. It is a simple heat pump etc. How do you think different burn rates are acheived? One way is through different formulations and different amounts of retardants. Other ways include grain geometry. Its all in the book I KEEP TELLING YOU ABOUT!!!
You still aren't talking about the ref I'm talking about "GUN Proplusion Technology". Can you quit talking about some stupid website?
Finally, tell me who this chemist is, and his area of expertise!? Is he a physical/theoretical chemist (like myself)?