I wuz up 'til the wee hours of the morning paper-whipping some ballistics using QuickLoad, and made an interesting (at least to me ) observation. Looking at the .308 Win. and the .338 Mauser Ackley Improved , I3031 comes out as the "best" powder in almost ALL bullets. In the .257 Roberts Ackley Improved it was I4350. Of course I need to define "best", so here it is:
 
QL provides a table of potential powders based the specs of the cartridge and some initial input parameters. Some of the specs are:
 
SAAMI max pressure;
Cartridge OverAll Length;
case capacity;
specific bullet, and so forth.
Some of the input parameters are:
seating depth;
load density (percent of case filled);
barrel length, and so forth.
 
 
The output is a table with columns that show:
 
the the name of the powder,
the charge,
the load density,
the resulting muzzle velocity (MV),
the max pressure,
the % of the charge that burns before the bullet leaves the muzzle,
barrel 'timing' (bbl harmonics related to departure time of the bullet), and
pressure at the muzzle when the bullet leaves.
 
 
Often, there are more than 100 resulting powders that have 'potential' based on the input criteria and cartridge specs. While thorough, it's tedious to sort through those, and many of the powders are either European or Australian powders. Some offer high velocities, but use load densities up to the max I allowed (110%) AND burned as little as 60% of that powder before the bullet left the muzzle. Sorting through what was "good enough" was tough under those circumstances. So... I decided to 'contrive' an objective method for scoring the various suggestions.
 
 
First, I'm not interested simply in the powder/charge that gives the highest MV. Neither am I obsessed with "efficiency" (defined below), but each of those components have some value to me. So... I calculate the muzzle energy (ME) for each powder selection in the table. Next, I divide the ME by the charge. This results in what I call "efficiency", (units are ft-lbs per grain). To come up with a 'score', I add the, muzzle velocity and % of the charge burned before the bullet leaves the muzzle, subtract the charge weight, and multiply that result by one one-hundredth of the "efficiency". The resulting value is the "score". I then sort the data by "score" ranking them from highest to lowest, and eliminate those powders (foreign) not available to me. I also eliminate all powders whose MVs were not within 100 f/s of the max MV.
 
What I found interesting, was that for the .338 MAI, I3031 was the top choice for all bullets selected. In the .308 Win, I3031 was also the top choice or within the top three. Furthermore, I3031 didn't even show up in the list of possibles for the .257 RAI. In that cartridge with one exception, I4350 was always the top choice. In that one exception, it was still only down to third place.
 
"So what?" you might legitimately ask. Well, the "what" is that with literally hundreds of powders available today, and all the hoohah spewed by "gun writers", it is often difficult to sort the wheat from the chaff. I had no predetermined favorite powder chosen for any of these cartridge/bullet selections. In fact, for the .338 MAI, the powder I used to do the actual real-world load workup, didn't even make the final cut. It wasn't within 100 f/s of the top MV.
 
So... I'm gonna try some I3031 in the MAI and .308 Win., and some I4350 in the .257 RAI. AND, I'm going to do this little exercise for some more cartridge/bullet combinations.
 
7x57 (100, 115, 139and 165),
8x57 (125, 150, 175, 185, and 196),
6.5x55 (90, 100, 120, 130, 140 and 160).
 
Then I'm gonna start looking at the wildcats I've "designed" on the 8x56R case.
.323 (125, 150, 175, 185, and 196),
.330 (150, 175, 205, and 220),
.338 (160, 175, 185, 200, 210, 225),
.358 (180, 200, 225, and 250),
.366 (250, 270, 285, and 300). :D
 
It'll be interesting (at least to me), to see if a consistant "good" powder is ID'd for each or any of these cartridges, AND to see if "efficiency" goes up or down as bullet weight increases.
 
Paul
 
Oh yeah; in the .338 MAI, "efficiency" goes up with each heavier bullet:
 
160g-63 ft-lbs/gr,
175g-64,
185g-66,
200g-67, and
210g-67.
 
As it does in the .308 Win:
 
110g-59 ft-lbs/gr,
130g-62,
150g-63, and
180g-65.
 
In the .257 RAI, it goes up and down:
 
75g-48 ft-lbs/gr,
85g-46,
90g-47,
100g-49, and
115g-51.

Man Paul do you ever sleep?  I was gonna say "get a hobby" but it appears you already have one!!! lol
 
I'm curious how close the same would hold true to other calibers based on the same case as the .308...ie the Rem .260, .243 win, and the 7mm-08?
 
Mike

Quote from: EnglishMan Paul do you ever sleep? I try not to.
 
I'm curious how close the same would hold true to other calibers based on the same case as the .308...ie the Rem .260, .243 win, and the 7mm-08? Good question. I'll 'run a few numbers' and see what I get.
 
Mike

Paul plus 5

Paul,

Well, that to me is some interesting info!  Over the years I have used a number of different powders for various cartridges.  My most used powders are AA4350 and H-4831sc and VV150 as the new kid on the block.  Have some 4064 somewhere ..... never used it however!  For the little .223 Remington...well, got such good accuracy with BallC-2 I just never tried anything else.

Look forward to posting of your results, my friend!:D

Ol' John

John,
 
I need everybody, (including myself), to keep in mind that this is a "paper" exercise, and as such may not resemble reality when it gets right down to it.
 
The author of QuickLoad has had to make some assumptions, and we do not know what those assumptions are. What I DO know is that with the loads I have run through QL for the cartridges for which I have chronograph and pressure data, QL cannot "get" to the velocities I get without exceeding the pressures I measure. In other words, it underestimates both velocity and pressure. Not terribly, 50-100 f/s and 10% of pressure.
 
Getting the pressure and velocity numbers to match requires significant manuipulation of the powder characteristics. Since I'm not a powder chemist, and don't even play one on the internet, I don't know if those manipulations are reasonable or not. What that means is that when I move to other cartridges and perform other analyses, I don't know how the author's assumptions effect those results, since I don't have measurements (chrono or pressure), with which I can verify them.
 
"So", you might ask, "Why bother if the numbers might be voodoo?" Because... I'm assuming that the assumptions made by the author effect all the powders similarly. Therefore, while the absolute values, especially for velocity and pressure, aren't likely "real", the relative differences between powders should be. That assumption - that the authors assumptions affect all powders the same - is one that cannot be tested, and means that these "results" of my QL analyses need to be taken with a healthy grain of salt.
 
One powder that has yet to show up is 4831. That concerns me a little, because 4831 has been my "go to" powder for the better part of 30 years. It's just a very versatile powder. It's absence in these analyses is suspicious.
 
Also, I have tried (meaning actually loaded and fired), I3031 is several of the milsurp cartridges I have, and it has never proven to be as good as several other choices - N-135 and N-150 as prime examples. I3031 is alway touted as one of THE powders to use in milsurp cases (BL-C(2) and 4350 being the other two), because it is supposed to so closely resemble actual milsurp powders. While I have had good luck with BL-C(2) and 4350, I haven't had such good luck with I3031. I woudl note that 4350 shows up in the QL analyses as much as I3031, and usually in the top three choices.
 
Finally, the reason I'm really performing all this analysis, is that I'm trying to get a handle on barrel timing. QL predictes the exit time of the bullet, and based on Chris Long's theory regarding the barrel "shock wave", I could use the QL timing information to select potential powders and starting loads. I DID NOT include 'timing' in my figure of merit equation (the selcetion criteria I mentioned above), because I haven't had time to figure out how to incorporate it yet. When I do, it might change the outcome significantly. WE'll see.
 
I've figured out a way to post the data better, but it'll take me a bit to format it. When I get it presentable, I'll post it here.
 
Paul

6.5x55 Data
 
mc - charge in grains
fill (%) is load density - percent of case capacity used by charge
vel(fps) - muzzle velocity
Pmax(psi) - chamber pressure in pounds per square inch
Z(%) - percent of powder burne dbefore bullet leaves muzzle
t(ms) - timeit takes bullet to exit barrel in milliseconds
Pmuz(psi) - pressure at the muzzle in PSI
ft-lb/gr - "Efficiency" = muzzle energy divided by charge
Score = -mc -((maxMV-MV)/2)+Z+"Efficiency"
 
Paul

7x57 Data
 
Paul

8x57 Data
 
Paul

.257 RAI Data
 
Paul

.308 Win Data
 
Paul

.338 MAI Data
 
Paul

.338x56R Data
 
Paul

The 3031 does seem to do quite well. I am most interested in the 8X57 and 257 AI. I guess that it's time to start playing and see what I can do with this new data.

Paul, I appreciate what you are doing but....
 
I don't understand how you can figure the timing of a barrel outside of actually putting several rounds of a said charge through it and seeing how it performs.  Maybe I"m missing the point here but there are so many variables that I don't see how a scientific/mathematic formula can predict this.  Variables such as the thickness of a barrel for instance would totally throw any formula off...wouldn't they???
 
I'm not stating facts so much as I'm asking questions.  I am genuinely curious how this exercise can be successful/helpful.
 
Mike

Actually, Mike it's not that difficult at all, and your mention of "thickness of bbl" is a good example of a widespread misconception about bbl timing. Instead of reinventing the wheel, let me point you to Chris Long's site about bbl timing. It'll answer a few questions that are likely to come up in this discussion. http://www.the-long-family.com/OBT_paper.htm That said, let me explain a few of the elements that go into predicting when a bullet leaves a muzzle.

The most straight-forward element of determining when a bullet leaves the muzzle is simply the muzzle velocity. If you know how long the barrel is (d)(and we do), and if you know the velocity of the bullet when it leaves the muzzle, then the simple t = d/r (time equals the distance divided by the rate (velocity)) gives an estimate of the time it takes the bullet to leave the muzzle. As I'm sure you know however, this equation assumes a constant velocity (r). We have more information however - the pressure/time curve. This curve is derived from having a pressure sensor on the firearm. The shape of the pressure time curve allows us to estimate the accelleration of the bullet from zero to muzzle velocity. Knowing the accelleration greatly improves our estimate of where the bullet is at any point in time.

Equating the P/T curve to precise estimates of accelleration is mathematically easier said than done. It is affected by many variables, such as the bearigng surface of the bullet, the diameter (caliber) of the bullet, the bullet's coefficient of friction (whether the bullet is copper clad or solid lead), etc. However, these are all measurable quantities. THe equation for departure of the bullet from the muzzle, with all it's intricacies, can easily be tested by placing a ressure sensor atthe muzzle. Exact bullet exit timing is then measured, not estimated. If necessary, the model (equation) is modified until it matches measurement.

So much for the bullet's motion, what about the characteristics of the bbl? In fact, other than the effect of the bbls metal composition on the coeffient of friction, the shape of the bbl is relatively immaterial. I realize that sounds heretical, and even flies a bit in the face of more than a century of lay observation. However, when it comes to the effect of the bbls motion on the bullet's point of impact, (incorrectly but most often referred to as "accuracy"), the bbl's metalurgy and profile are in fact almost irrelevant. Here is in part why...

The steel used in bbl manufacture is sufficinetly similar across ALL forms, that the speed of sound can be treated as a constant. In other words, the speed of sound in stainless steel for example, is not sufficiently different from the speed of sound in 4140 to matter one whit when it comes to vibration timing. And the speed of sound IS the most important factor.

Consider what would happen in a bbl if you struck it with a hammer. A shock wave would travel from the point of impact to the ends of the bbl. If you struck it at the breech, the wave would travel from the breech to the muzzle. The speed that wave would travel is independent of the shape of the bbl. PERIOD. Here's what's important about that.... That wave would get to the muzzle, and reflect back toward the breech. When it again reached the breech, it would reflect back toward the muzzle. And so on until it had no energy left. When you fire a bullet, you are effectively hitting the breech with a hammer. Granted, a hammer shaped like a bullet, but a hammer nonetheless.

The optimal barrel timing theory posits that the best "accuracy" is realized when you can time your bullet's departure from the muzzle to a time when the acoustic wave is farthest from the muzzle. When the acoustic wave is at or near the muzzle, the muzzle is most distorted. That distortion affects "accuracy". And there is why I don't consider this exercise to be one in futility.

Of course, hunters have gotten along for centuries without this level of analysis, and I would never suggest that one needs to perform such complicated gyrations in order to have a rifle that "puts 'em where I aim". Nonetheless, I enjoy this type of work, and my interest is in finding an optimum LOAD. One that gives a good MV while at the same time puts the bullet out the muzzle when the acoustic wave is some distance from the muzzle.

There's more to this than explained above, so if the above explanation leaves you with more questions - even challenges - by all means, let's discuss it further.

Paul