Ron,

If you want some help understanding the calucaltion of internal ballistics, send me a PM.

ASS_CLOWN

AC,
Thanks for the offer.

Since George S started PM-ing me about retracting my "attacks" on NNN's character (What character? Rather lack of it!), I have disabled my PM feature. Glad I didn't make any retractions. Why retract the truth?

Guess I am just another asshole cluttering up the threads with trash here, according to George S, like so many others here, according to George S.

I would rather be given the boot in public on the forums than cave into a lying nattering naybob of negativism like NNN.

I think my email is in my profile.

Really now, why don't you let everyone benefit from your expertise in pressure modeling/calculations?

If we may start that in this thread or another then let me know, either here or in an email.

Thanks.

Ron,

It was not my intention to actually teach a class, I fear I am not qualified for that. What I was thinking of providing some pointers and curves so that you could get more information from your measured chronograph results. In doing so you would learn the 'basics' and be able to expand on the information I provided.

By the way, your profile lists no email.

We can discuss it in the public forum, but with my reputation as an ASS_CLOWN I fear disruptions (perhaps not a bad thing though, eh).

ASS_CLOWN

AC,
I added the email that I forgot was not displayed.

For starters, how does bullet mass alone affect pressures, all else being constant? Hypothetically speaking, of course.

Seems like something as basic as F = ma might be involved somewhere in this?

Thanks.

.

Hey AC,

If I may make a suggestion, instead of discussing mathematics here, now is a great time to register and study for ASE certification. Deadline to register is still a couple weeks away, and the test isn't until May, so you have a bit of time to study as well.

You can even register online

Then you can start making more $$ to start buying some of the stuff discussed here.

quote:

Originally posted by ALF:
I for one would be most interested to see where this one goes.

Probably along the line of malerial hallucinations.

quote:

Mark, I see no benefit to getting certified, as my boss tells me he ain't gonna pay me more.

AC, then find someone who does! There are TONS of employers out there who can use skilled mechanics.

Register for the exams

Order study materials

Study 1/2 hour a night

Take the exams.

Pretty simple, plus, I bet if your shop has any size to it at all you will most likely get the test fees paid for.

Dude, spend your time improving yourself first, then you'll get the paybacks later. But don't kid yourself, you are better off at the moment concentrating on getting certified rather than discussing ballistic and recoil theory.

quote:

Originally posted by Paul H:

quote:

Originally posted by ALF:
I for one would be most interested to see where this one goes.

Probably along the line of malerial hallucinations.

AC,
I see the hecklers are going to come out to play.

Paul H ought to at least spell correctly (malarial not malerial) if he wishes to put on airs of superiority and disdain in casting aspersion, eh?

You have given me some good thoughts to work with, so I will break out the basic physics and math and have a go.

My special branch of math called fudgealculas,
used for big straight cases;
the formula for Mean Barrel Pressure is as follows-Once you have MV---And is accurate to 5%.

MBP= Velocity squared x Bullet wt, divided by

30000 x barrel length; all divided by

Bore squared x .8.

Simple math and once you
have MBP, for most regular powder pressure curves(not for squib loads),and for the slower type powders I use in my cases(4320, slower)then you divide by 3 to get muzzle pressure for stick powders, divide by 2.5 for muzzle pressure for ball powders, and multiply
by 2.5 to get peak pressures for stick powders,and multiply by 2.3 to get peak pressure for ball powders.
And then you can lay out a fairly accurate
pressure curve on graph paper.

Like RNS 550 MAG load in other thread, 700gr
bullet at 2300 fps,26 in barrel.Formula gives
19,700 psi MBP, giving 7800 psi muzzle, and
45,300 peak pressure, for ball powder.
oOr for stick, 6600 muzzle,49,250 peak.Ed.

.

Alf- That last chart tells the story for
us big bore nuts, as it shows the power
we can get at much lower Mean Barrel
or Mean Effective pressures,Just look at
the difference between the 458/470 and the
550/600 classes. We here at AR are on the
best big bore track, as to getting the
horses so to speak out of shoulder arms.
AND YOU EXTEND CHART TO THE RIGHT,ADD 700s,
12GA FHs, 20MM, MY 900, 4BOREs, shooting
and gun building gets interesting....Ed.

Bravo, Alf!

Now you know the mental masturbation applied to the "other thread" where there was much sound and fury signifying nothing, and the noise of one hand clapping, etc. "The Thread" where most were just beating around the bush, including you.

But here you have done something useful for me, and I appreciate it.

That first graph and the simple equation would seem to indicate a straightforward linear relationship of bullet weight to pressure, all else being equal, for the appropriate charge for the given case and powder.

I think this will nicely support my .404 Jeffery Varget loads with North Fork bullets in my rifle as being SAFE.

AC's previous SWAG pressures still sound good to me too, however he did it.

The low "MBP" and high energy for the big bores is interesting, as Ed pointed out.

Thanks.

How does one go about finding these articles that you are excerpting here?

RIP, no heckling here, but I can clap with one hand...

.

Alf- Those multipliers for peak pressures are for straight cases only,soft jacket bullets,
and hold pretty accurate in my straifgt cases.For solids add 10% to the factors..\Multipliers are not for his 404
or the 416, 460, 500J, 505, etc.For those cases
add 15% to the multipliers.
AC- Your right some powders do change burn rates(even fast ball) as
powder volume goes up, and powder column
gets longer, sometimes drastic changes.
like some in my developement of the 458 HE,
as I used in cases from 2.5 inches long,
up to 3.45 inches long and the velocity curve
got over twice as steep on the longer cases,
with these certain powders.
But I do not concentrate on cartridge developement in the 62k range, to have that problem,IE don't push
those loads and pressures.

The powders that did that also reacted to
bullet wt increases the same way, compared to others.In these examples of heavier powder charges, and bullet wt increases, the extra time and turbulance in the initial combustion affected the deterrents on the powders and they gained speed, IE higher burn rate than what they started out being manufactored as.

Now with ball powders you mention the rate changing as pressures go up isn't all bad,
as the basic characteristics of most ball powders I use sets the peak pressure occurance
at about 50%(sometimes more) later than stick powders of the same rated speed, then when pressures climb due to larger volumes/ longer
powder columne,as long as you set it right(IE
don't overdo it),
the gain gives better velocities than stick,
as it is making the peak on the pressure graph more rounded, and adding more area under the curve, and due to the later occurrence of peak pressure brass lasts much longer.Even though of longer duration it isn't as sharp, and the sharper peak pressures stretch brass more
than a little higher later pressures.

In my 458HE,long barrels,load testing;
500 gr soft jacket bullets
full loads of W-760 at 2800 fps, gave me 15 reloads and starting loads of 4350 half that many, in 500 gr bullets, at only 2550 fps.Ed

.

quote:

AC,
Thanks for the offer.

Since George S started PM-ing me about retracting my "attacks" on NNN's character (What character? Rather lack of it!), I have disabled my PM feature. Glad I didn't make any retractions. Why retract the truth?

Guess I am just another asshole cluttering up the threads with trash here, according to George S, like so many others here, according to George S.

In fairness to George S, he cannot be blamed for asking your retraction (although I do not know how he asked you)- IMHO, it was probably a reasonable request- while 500 grains may have put you off in some way (and maybe others too ) , I am sure deep down inside he is a decent guy like all of us- but like all of us, we have some quirks and issues at different levels

All this to say, it is really none of my business nor is it really an issue, but I feel, as a forum member, that we should try to smooth things out as needed- besides, what if I need to P.M. you??

Ofcourse the reason cases hold with rating of 14,000 to 22,000 psi burst rating is the chamber
has a huge rating to hold the radial forces.
And the force in the corners is held by the radius of the brass from sides to base, being much thicker(Sides being held by chamber and base by the breech)Thus giving a much bigger stress ratio, compared to chamber pressure,
in the case corner.Except(tongue in cheek)
some cases I checked for wildcatting, where corners were only marginally better than the sides.

On another thing you stated that comparing peak pressures for stick and ball, relative to muzzle energy produced that stick would
have more energy. that is absolutely wrong,
and I have hundreds of rounds, and 19 different powders tested that proves with same peak pressures DB Ball produces more muzzle energy.
In all that I compared in same bullet wts.
Even at higher pressure levels over 55k.Ed.

Excuse me, but since when have double base powders contained less energy on a per gram basis than single base powder?Did I miss something or when did nitrocellulose begin to have more energy on a density basis than nitroglycerin.-Rob

ADDED INFO- THIS POST IS A REPLY TO
AC POST HE REMOVED, AS WELL AS A WHOLE.
And he removed a bunch of others that I
replied to,Thought readers should know
that I am not talking to myself in the
answers I give.

Go look at comparitive pressure curves for stick and DB ball, at same peak pressure.
All the Db powder I used,compared to stick at same peak pressure, that I used, has more area under the curves, hence more velocity, more energy.The DB ball has more energy, up to the highest pressures I tested,compared to stick.
In all comparisons to get same peak pressurewith DB ball, it took a small percentage more powder by wt to do it thus it only stands to reason that ball load at
same peak pressure will have more energy.
Also,as Rob says the energy per gr is more.

I gave you the multipliers in posts above,
for the range of pressures I developed my
cases at.For the powders I used.There was no fast powders of either kind.No reason to use them as they'd be unsafe for big cases.And I added info to use with multipliers for solids and shouldered cases.My velocity formulas I used with chrono readings gave me peak pressures.- in conjunction with case condition,extraction, etc as I had for
testing after getting started cases that were soft.

As far as applying strain energy math to determin stresses on the case corners is too complicated.I like to keep math simple.
All the math I fudge, allows folks to take
only a minute to do and easy to understand.

Rob,

Could not agree with you more.

Ed,

You seem to be dodging my question though Ed. How did you measure all these pressures.

ASS_CLOWN

Ac- the only time the fast ball powder types
I used, made big excursions to real high pressures; was when peak pressures started getting over 57k. When Mean Barrel Pressure
was getting over 22K. You can see from the example I gave above of the 550MAG loads
done so far, running at 20k MBP, that they
are just getting started and have a lot of room to go up without pressure problems.They will get velocities that will scare the shit out
them.Same with the OK.And their cases will fall out, after firing.SAme with 700HE.
I'm not dodging you on how I get pressure figures, First the chrono is the measuring tool/The best tool by the way for ease of operation and using with my math..I putinfo in the velocity formula, the one with the 7100 7400, 7700, 8000, 8300,
8600,etc, fudge factors,expansion ratio factors,
etc and if it chronos as I figured ok if it chronos up or down I run formula backwards and have my pressure.And it works as I correlate it with the
formula for MBR.It works great, and never blew a case or stuck the bolt tight(and had soft brass after testing was going, and discounted results from the few hard cases I had)-- except when I accidently shot out a half lb rod, with a 110 gr of H380.Have had cases extract a little hard but my system allowed me to get up to where pressures started going crazy without mishap, and able to develope loading trends.
And then back away.I am using case designs from scratch that no info is out there for, so my careful system seems to work.ED.

Well,
I guess I am back to looking for my own strain guage for my own rifle.

Cheers!

.

Alf-Both types of powders have retarders,
so as too make them propellents as opposed to
an explosive, which would propagate gase way
to fast
and a super high speed wave front and blow up the gun.DB has nitoglycerin added, ie disolved in the nitrocellulose, to
add more energy per grain, per actual volumne irregardless of the shape of the powder, and the action of the retarder makes the release of this extra energy help to put more energy under the curve later in the combustion process,
especially in DB Ball. Hence more
total energy for DB Ball.The stick powders being hollow, burn inside and out and
can't be slowed as much as ball for the initial
combustion phase, thus the sharper pressure peak in comparing both types of powders of same speed.But overall total energy is in favor of
the DB ball powders.
Some of the DB stick powders won't have anymore energy per volumne than nitro only due to the fact of their constuction IE that they have
larger holes and grooves and thus less
density in actual use in the chamber.
Example is RL-19 at .89 density,
compared to 4831 at .93 density/they come out about the same in energy, even though the Rl-19 is lighter on a
volumne basis in actual use, it has extra NG added.
SO that is why I like DB Ball.Its heavier and more energy per volumne in actual use.The
density is .94 to 1.01 of the ones I use.Ed.

Ac-I have figures from the powder chart in Handloader digest-RL19--.890 -- 4831--.930..
They are only 3 places apart on the chart, with
rl-19 a little faster and in my loads it
was only 3% faster.I was using them as a comparison.You know AC you being so damn picky about all this math and its application, wanting everything to be accurate
to .000000000001%, is crazy. Ballistics don't work that way. Common sense application of easy to understand math and principles are what is safe.If you take top load you read or heard about in a particular loading, and don't work up to it like I do, fire it in a gun with
strain gauge, wanting to get the most accurate info, and something lets loose, what has best accuracy of the gauge gained you.My simple math is a way to get there safely.

In example above where I used my math on
the 550 loads, multiplying the MBP by 2.3
to get peak pressure for ball , and if
you shot a load with strain gauge, and it
gauged out to 2.3245678, who cares and
it wouldn't matter as the next shot would be different like 2.29234567 and so on. And as MBP got up so peak pressure was around 55k and the same tests showed 2.38321 for example and so on, it don't matter, as the simple math applied
will get you safe loads."Applied" is the word,
in the cases I do that no one has built.
In the case of the 404 Ron wants info on, if he measures water capacity to base of whatever bullet he wants to use, at the COL he wants , it is easy to figure a good load for max energy with lowest pressures, as long as he has a chrono.Using simple calculations.

PS- please explain your PRM formula a little better. Even confuses me, some of the terms and letters.

I may have to teach you guys something about significant figures( pardon me AC I know this is your area). I doubt any measurement except one of weight, distance or an electrical one(voltage or current) can be relied upon to more than THREE sig figs. Those three and maybe rediation decay values are the only absolute measurements I am aware of) As I remember AC actually works in a QA role of some sort and I believe he will agree on that point. Just because your calculator reads off 8 figures doesn't mean the measurement is accurate to that level. Moreover, if you multiply or divide by anything less precise ( i.e. fewer sig figs. You can only rely on the results at the lower limit. Thus even though a strain guage can read to 6 decimal places doesn't mean that the results are reliable to six decimal places. More likely its reliable to three at max. Now you have the problem of standardization. Just how accurate do you think a SAMMI std pressure cartridge is?
Two sig figs maybe three? I've been through all of this crap before and while a interesting aarea for argument (AC loves this one for sure)
In the end who cares really. Because of all these inaccuracies in pressure measurements you wind up with relying on proof loads and then if it all holds together staying well below those limits on an operational basis.
ED- You are absolutely right on the chemistry of powders and the amount of energy available per gram.-Rob

Rob,

Denton is in QA, not me. I am just a simple uncertified mechanic. Pressure were rounded to the nearest 100 psi, and charge weights to the 0.1 grains. I typically only use two to three significant digits on the PRM (pressure ratio multiplier).

ASS_CLOWN

Ed,

Deleted as it has served it's purpose.

ASS_CLOWN

quote:

Pressure Ratio Multiplier (PRM) = [8.7428E-5 * (26507)] + 0.102 = 2.42 (bigger than 2.3 eh, imagine that!)

I would use 2.5 myself as it is a stick powder
that isn't as dense as the Slower Ball powders
I use or even most single bases ones..So what is problem.Due to the way RL
powders are, they are not like what makes a good DB powder compared to ball.I don't
like them.

Now explain the math in the rest of the quote.so a layman can understand it,IE how
did you get the 2.42 PRM. Explain E, Is * a
symbol for times. I use x so folks can understand..Man you got to work the stuff out so gun nutz who are not college pofessors can
understand.

For the 550--
explain what formula you use to get get
over 26K MEP and show what you did.That is way too high.The correct formula shows about 20k
as I showed above for 700gr -2300 fps--26 inch
barrel with the formula--
MEP=[Bullet wt x Vel squared] divided by
[barrel length x 30000] all divided by
[Bore squared x .8]

Put in info--[700 x (2300 squared)]
divided by [26 x 30000] all
divided by [(.550 squared) x .8] = 19.600 MEP

Or MBP as I call it.These figures aren't super exact they are a guide, within 5-7% to use to safely develope loads.

Ed & AC
How about I invite the two of you to my house (neutral ground) and let you work it out face to face? Either at the table or wrestling on the floor . I think the entire conversation is interesting (even though I probably won't ever need to use the information).

AC- Well at least we are getting some agreement.
Your MEP now is similiar to mine for 550 speeds.
And the formula you use for MEP is the same one
I used to make the simpler one, after I refined it.
In the math on mine I added correction for the
barrel friction, so mine will read a small amount higher.

BUT THERE IS NO WAY PEAK PRESSURES WILL BE
AS HIGH AS YOU LISTED FOR MEPs OF 19-20,000 PSI,
with the slower powders that we are using,, on straight
cases, especially a short one.The slower powders we
are using are on the last page of a 3 page list.
Slow in the overall scheme of things......That 3.3
multiplier is more like what would be used for 4227, etc.
On straight cases the multiplier will go up a little, when
MEP gets over 24 to 30 k, up to 2.5 for ball, 2.8 for stick.
But then peak pressures are up around the 70k range,

If the 3.3 multiplier was right, then if MEP went to 25k
in 550 MAG and the multiplier going up following your
trend would be close to 4, making peak pressure
100k..No way..,.If your 3.3 is right they should have sticky
cases and bad recoil now....but cases extract easy, and recoil
is like a pussycat. That 3.3 multiplier would be similiar to 460,
a necked case, full load with heavy bullets.
Something is wrong on those multiplier formulas.Ed.

AC,

Did RIP drop out or did you flunk him?

Some of Brownells work at UofM was puplished.
"Firearm Pressure Factors" 1990 Wolf Publishing Co.
Good luck!

AC you are wrong.Look at Alf's chart again for
the 560 bore line AT 20k MEP is 10000 ft lbs.
A 550 line would be slightly lower at about
96-9700, for a 20kMEP The the 510 is almost 8300 ft lbs.Your closer there.
I drew that chart out on a big graph, so Iknow
what those calibers will do.Calling the value for 550 one eighth too low to make your math work ain't kosher. Or you need glasses.The chart don't lie...
Whoever is setting the multipliers for the powders you mention are
doing it for necked cases, they're not for our straight cases , using the powders we are using.

IF in example for the 19-20,000 MEP, for
550 , the peak pressure was 63-64,000 psi as you say, then if using my velocity
formula which is an extension of Homer's velocity formula; based on peak pressure, bullet wt, powder wt, ex-ratio, etc the velocity would be
close to 2550 fps.But it is 2300, another
proof you are using wrong math.But you take
a 20,000 MEP times my 2.5 multiplier to get
peak giving 50 k and put that in velocity formula and velocity comes out at 2300.
AND That is what their chrono says.
Another proof.With right stuff they will
get 10,000 ft lbs with peak pressures in the ranges you are quoting......

AC,I will make this concession, IE if your multipliers are more right than mine, then my formula for
MEP(MBP) is too high. IE, I might have made
too much correction for friction.So if
as you said above that muzzle velocity is
correcting for friction(which we told you on
the recoil thread, and I know is true.), then without coreection
in my formula the results for 550 at 2300
would be
16800 not 19600 MEP .Then the multipliers
to be used for peak pressure would 2.7 for ball and 3.0 for stick powder.But your figures for MEP were close to mine.I am willing to study to figure out the best setup.. .Ed.

quote:

Originally posted by hawkins:
Some of Brownells work at UofM was puplished.
"Firearm Pressure Factors" 1990 Wolf Publishing Co.
Good luck!

Thanks for that headsup.

I don't have the time or inclination for all this number crunching.

Even if I do get a strain guage, the method I am thinking of still requires calibration, to a standard load. It is not an absolute, real pressure in my rifle.

So I am back to old school.

I have shot the 90 grain Varget load with no signs of problems for five shots. No sticky bolt. No brass extrusion or ejector slot marks. No abnormal primer appearance, no primer pocket loosening. No case head expansion detectable by me. No wild velocity variances in working up, just a smooth linear progression of about 30 fps per grain of Varget.

Then I dropped back to 87.6 grains, just because. I have fired 40 rounds of that with none of the above problems.

I have learned some good stuff from this thread, and it is much appreciated.

The liar (Nattering Naybob of Negativism, yes that means 500groans) may go straight to hell, do not pass go, do not collect $200

RIP- What bullet wt are you using with Varget
and do you have chrono.If not the 87-90 gr
will be safe.Main thing is getting good accuracy
with power.Ed.

quote:

Originally posted by hubel458:
RIP- What bullet wt are you using with Varget
and do you have chrono.If not the 87-90 gr
will be safe.Main thing is getting good accuracy
with power.Ed.

Thanks Ed,
Your judgement is same as mine. That load is with the .423/340 grain North Fork, a grooved solid copper shank with bonded lead nose core.

87 grains was 2683 fps at 40 degrees F.
90 grains was 2768 fps at 40 degrees F.

Really, just watching the chronograph and watching the brass and primers over the course of 3 loadings is about as good as it gets.

Each rifle is a law unto itself anyway.

I am back to simple estimations. I won't go any higher than 87.6 grains with that bullet. That load has proven to be accurate in my rifle.

87.6 grains Varget Extreme:
40 F: 2699 fps
50 F: 2704 fps
100F: 2729 fps

Of course, any time you change the lot of powder, any previous pressure readings are out the window and need to be established again for that rifle.

So why bother unless you are a commercial manufacturer with liability concerns? I take responsibility only for my own rifle and my own ammo.

But for enlightenment and entertainment purposes, your discussions here are quite good.

AC I POSTED THIS ABOVE---

"AC,I will make this concession, IE if your multipliers are more right than mine, then my formula for
MEP(MBP) is too high. IE, I might have made
too much correction for friction.So if
as you said above that muzzle velocity is
correcting for friction(which we told you on
the recoil thread, and I know is true.), then without coreection
in my formula the results for 550 at 2300
would be
16800 not 19600 MEP .Then the multipliers
to be used for peak pressure would 2.7 for ball and 3.0 for stick powder.But your figures for MEP were close to mine.I am willing to study to figure out the best setup.".

Now about ideal powders, that is why I use so many and add in all the the ball types which as you know 95% of shooters and gunwriters never use.If my formula based on experience for many loads, over many years of testing is high, thus giving to low of multipliers, then that may account for difference in our figures for peak pressure.I am willing to study to figure it out.WIth chart D scaled up the550 line I put on chart which I just noticed(LIGHT BULB), crosses the 8000
ftlb line(which 550 at 2300 figures out to)
and that is about the level of the 17,000 MEP
Line Across the Chart, so my formula without correction givng 16,800,must be more correct.That makes multipliers for peak
pressures 2.7 for ball and 3.0 for stick.
Which give peak pressures that my velocity formula shows the speed in the first place.
I am glad chart came along.If it is right- It may be smarter than both of us.Butyour MEP was up like my original formula.But if you think about it,that chart has to be close to foolproof.We are dealing with a linear relationship. which is what chart is showing.
I have made charts before like this for one caliber a time, for the wildcats I developed. but never had all calibers on the chart.

And another light bulb-- IF CHART IS CORRECT
AND FOOLPROOF THE ALL WE HAVE TO DO IS FIGURE MUZZLE ENERGY, PUT IT ON CHART TO GET MEP, USE CORRECT MULTIPLIERS AND WE HAVE PEAK PRESSURES.
Simple.A way to get MEP and peak pressures for
that particular gun and conditions.That we can also check back to compare to the velocity formula, and what the chrono says.

HOTDAMN PROGRESS. I should have done this years ago.So simple it makes me feel stupid.THe most important thing I have learned in years.
Seems foolproof to me,IE velocity used to figure ME, is correcting for smooth or rough barrel, tight or loose barrel, min or max chamber, temperature, etc, so figure ME based on chrono velocity, and use chart giving MEP for that particular gun and conditions.If you do it tomorrow at 100 deg colder velocity changes and so does MEP, and peak pressure figured from it, which is what happens in the real.Using this process the 404 load above at 2700, 340 gr bullet, figures out on my scaled up chart at
20,500 MEP, and about 60k peak pressure.
With the Varget powder.If he had done it with
ball getting same MEP, then peak preassure would be about 55k. Ed