Please bend my ear on powder selection.

[MBTcustom]

I recently got a copy of quickload and used that program as well as a chronograph, to decide what powder would just fill the case, and give full speed potential for 358 Winchester.
I found that IMR (or Hodgdons) 4198 fit this criteria exactly, so off I went to the range with a selection of cast boolits as well as some Hornady 200 FTX just for good measure.
I loaded up some cartridges with IMR 4198 and shot them over the Chrony, adjusted the burn rate to match the speed I got, and then tried to shoot a group with my brand new MBT built;-) Sako AV. The results were pretty raunchy. About a 4" group at 50 yards loaded hot or loaded cool.
It was a new rifle, and I figured it was possible that I made a mistake on the build, so I tried the Hornady FTXs. About a 1" group at the same distance (ie terrible!). I tried several different loads with both the 4198s, and I got no love from either. I went to my old standby (IMR3031) and a load of 38.8 grains in LC match FL sized, gave me .78 MOA (ie acceptable in my book).
So this leads me to my question: Why does one powder work like a charm, when it is actually too voluminous for that case capacity, while another, that seems to fill the case perfectly and produce the correct speed, turns the precision rifle into a shotgun?
What does the 3031 do that the 4198 does not?
Is it possible to predict (without going by hearsay) what powder will work best in a certain gun?
If so, I would like to know how to do that. I want to be able to make educated guesses that will get me pretty darn close to where I want to be.
How does barrel length, case capacity, projectile hardness, and pressure effect the selection of powders.
Someone must know. Please bend my ear with what information you have.
Thanks!!!

[Mooseman]

Different powders with different burn rates make a barrel vibrate differently when fired, and there are other factors that come in to play as well. In some longer barrels i found they liked a slower burning powder and some shorter barrels needed a really fast powder to get them to shoot accurately. When I shot competition , it was a lot of trial and error testing to dial in a load to a specific gun or Contender barrel , and sometimes slowing a bullet down produced sub MOA accuracy. In other cases, a particular bullet performed better when run faster like a 62gr. vs a 55gr. in a .222 barrel.
Even bullet seating depth and amount of crimp can change POI as can different batches of brass .
Also temperature and humidity have an effect too.
My motto for many years has been "when you change A , it affects B, which also affects C" !!!
Also I have seen new barrels that took many firings to Break it in and tighten the groups.
Rich

[Bullshop]

"""What does the 3031 do that the 4198 does not?"""
Slower burn rate = gentler exceleration
"""Is it possible to predict (without going by hearsay) what powder will work best in a certain gun?"""
I think not. Cartridge maybe but individual gun I doubt.
"""How does barrel length, case capacity, projectile hardness, and pressure effect the selection of powders."""
I dont think you can look at those things collectively and predict what would work best. I would think they can only be looked at individually as some will have little or no effect on the other.
For myself when developing a load first I decide what I want in velocity then try to figure out how to get there at the lowest pressure reguardless of case volume or barrel length.
If using a soft alloy the lowest pressure for the desired velocity is more criticle. With a very hard alloy the lowest pressure for desired velocity is less important and you might even notice that as alloy hardness goes up the pressure that gives best accuracy may go up as well. I cant say that this is a formula that always works for me but am saying this is how I go about starting the search.
EDIT
I always seem to forget to mention and take it for granted that I am talking about shooting boolits and not bullets.

[MBTcustom]

So no one has drawn any conclusions on what powder would be best in a particular rifle based on pressure curve or other data?
That's hard to believe. I figured sure that somebody had tested 600 loads in 30 rifles, and had come up with a baseline for powder selection based on case capacity and projectile diameter and weight.
I suppose that might just be a nice idea that's totally impractical, but still you would think that somebody has their minds wrapped around this.
I am not generally content being spoon fed information. I want to know why and how.
I know I can want in one hand and spit in the other and see which fills up faster, but I still want to know. Its a mystery to me.

[felix]

It is a mystery to everyone, Tim, because every steel, powder, primer, copper, lead lot is so different chemically, not to mention the machining tolerances and projectile form. Specs for BR guns are specific, and thus specific loads are prevalent in advance. The gun MUST shoot this load from day one to be worth the typical 3500 dollar price tag charged by the smithies in this trade arena. The cost of the gun and ammo is a nit compared to the travel arrangements for travelling to the matches. The goal is making total costs transparent compared to that of being a match winner, which is the ONLY objective. ... felix

[Bullshop]

There is one group that believes they have the answer. They shoot black powder in everything.
But even then they dont all agree if a certain case with a certain boolit in a certain barrel length should certainly use fg or ffg or fffg or?
I think its kinda like having a suit custom tailored to fit yourself. It fits you perfetly but wont fit anyone else nearly as well. Guns are the same way.

[felix]

That is very reasonable because the peak pressure of BP is weak compared to the total inertia of the shooting system. The only change would be where the peak occurs within the gun's barrel, and that is the argument you are witnessing. ... felix

[MBTcustom]

Its my nature to look for patterns in tea leaves I guess.
All I know is that it seems like for any given caliber, there is a short list of possible powders that are going to work. Usually three, and not more than five, (of course the data is geared towards jacketed bullets) and one of those offerings is going to give sweet fruition. You plot the theoretical pressure curves, and you get a slightly different plot for each one.
I noticed in quickload, that the one difference that 4198 had over 3031 and W748 (two proven performers in this caliber) was that it came up to pressure much quicker than all of the traditional loads for this cartridge. I printed graphs of all three and held them up to the light while they were stacked together, and could see the sharp rise with the 4198 that the others did not have.
Not that I am a scientist or anything, (I'm sure you noticed) but I just wonder if any powder of similar volume, burn rate, and pressure curve would be worth giving a try.
4198 had the right volume, and it had the right pressure, but it came up too fast, and I assume created a harmonic that buzzed the bullet/boolits the wrong way on their way through the barrel.
I don't mean to waste anybodies time, but this is what I'm thinking about right now.
Lets just assume that you are right, and its impossible to determine a load for any random rifle. Lets deal with one specific rifle that wont shoot very well with any of the conventional load data. I want to try a powder other than what I have load data for. Something a little faster or slower. What criteria would need to be considered?
All of this is assuming you have Pressure Trace equipment and were comfortable working with loads that there is no data for.
Not that I intend to engage in this sort of activity, or would ever encourage anyone to do this, I am suggesting we make these theoretical provisions so that I can get my head around how this works.
Another way to look at it: Lets say that one of the major manufacturers comes up with a radical new cartridge design. Its cool looking and will sell like hotcakes. Now, how do they develop load data for it?
Do they start with Clays and end up with IMR7828?
Oh that's right! most of them blend their own powders! I might mention some of the hybrid powders that have recently come available. Surely they are not fishing around in the dark, trying different blends?!?! I totally understand that the effect might not be quite what they were looking for, but I refuse to believe that they have no way to make scientific estimates of what is going to happen and why it happens.
There are thousands of factory loads that shoot quite well in a variety of guns. Usually any Remington firearm that is run with Remington ammo, will shoot less than 1.5" at 100 yards. For every gun being a law unto itself, that's pretty good accuracy over a large range of cheap guns.
It seems to me, that if the factories can put out full power loads that shoot that good in so many firearms, then we should be able to find similar data for our rifles. Certain combinations that always work. They might not give bugholes, but they will get you awful close.
I was actually surprised that the 4198 powder could turn a precision rifle into a scattergun at 50 yards. I didn't know you could make a gun shoot that bad!
If the rifles are really that picky, and even a bench gun would shoot a 4" group at 100 yards if the wrong powder is used, then how do factory munitions do so well?
They must be able to know for a fact that they have found a safe average right down the middle of most rifles needs, right?

[429421Cowboy]

Hmmmm.... I seem to make alot of sense out of what you are saying Tim! Back before i reloaded rifle rounds, i ran alot of different factory through my Rem 7mm rifle, for practice and finding what it liked. It hated the Rem Cor-locts, and did best with the Winchester Power Points, liked the Fed's. Yet the difference between how it shot with any of them was maybe a max spread of 1" at 100 yards between groups of what it liked, vs what it didn't, which isn't too crazy, even the Rem loads never produced anything looking like a buckshot pattern. So, agreeing with what you are saying, why do factory loads do so average with all rifles? I am betting my pet load of 60gr of RL-22 in Win cases with a CCI LRM and a 168 Berger VLD will shoot sideways in somebody's rifle, yet lands .5 MOA for mine if i can hold up to it. So how come factories don't develope a load that shoots minute-of-gnat in a test rifle, yet scatters for half of the factory rifles?

There has to be some science for it, or at least after as many years of experience and testing as we have here, there should be a good place to start for most rifles.
I lease pasture from an old cowboy who used to be a police armorer who loves to reload and shoot, who has often told me of his "accuracy" loads for .308 and .30/06. In other words if he ever had an '06 that he needed a quick load or couldn't get one to shoot, he knew he could use that specific load and it'd either shoot that or nothing at all.
So what makes a load good for the majority of rifles that factories can produce? Is there some science behind it?

[MBTcustom]

Exactly.
The thing is, I know there is science behind it.
But I don't think we get to use the same components that the factories do. I have pulled some ammo before, and what I found inside does not look much like any powder I have ever used before. I know there has to be someone who knows what the particulars are about what makes a good, ideal load. But that person probably does not hang out here.
I have been surprised before though.

[429421Cowboy]

It sounds as though you believe that there could be some sort of formula that would tell us what bore size+case capacity+pressure in some formula would point the way to a "perfect" pressure curve, peak, burn time that factories can use to blend this perfect propellent, that might be adapted to let us pick the ideal starting point? I had never thought about it this much before, but you do have my wheels turning! As you say, they can't just go at it willy-nilly trying things till it hits them. The more i hang around you guys the more i learn that NOTHING we do is an educated guess!

[smokeywolf]

Tim,
I think when it comes to working up loads for a particular rifle or pistol, it is not that much different from doing R&D in the shop. Even with 3D solid models and computer simulation software (I.E., Finite Element Analysis) you can enter all the variables but you can't enter all the unpredictables.
Most of my machining career has been as a Prototype or R&D Machinist. Other than one particular Engineer with whom I worked, I've always thought that R&D should actually be called T&E, Trial & Error. Variables can usually be factored in, but unknowns remain unknown until the final test. Or, in the words of one of our members; "It's all an educated guess, until the trigger is pulled."

smokeywolf

[MBTcustom]

NOTHING we do is an educated guess!

As little as possible.

I have been tinkering with the quickload program. The feller makes some outlandish claims that barrel harmonics can be predicted, and that by carefully modifying the program to your rifle, you can get really darn close to a sweet load right off the bat.
I bought a laptop and installed the program. I slipped the laptop into my shootzenwagon along with my press, bullets, boolits, powders, dies, etc etc etc. (I have to use a C-clamp, but I can get the kitchen sink to hang off the side right next to the chronograph.)
Anyway, I set up and began testing out the program.
At first blush, it seems like the guy is on to something! Using a proven powder for the cartridge I was working with, and adjusting the program as directed, it put me on an accurate load right away. (See my post in gunsmithing tips and tricks on Adams and Bennett barrels)
However, since 3031 was too voluminous for the case I was using, I decided to use the program to try to find a more ideal powder for the cartridges I was loading, and came up with IMR4198 as a perfect fit. It filled the case to the bottom of the bullet, it have adiquate speeds, and it was well within the pressure limits of the cartridge.
Unfortunately, the program failed miserably on this powder choice. Even with jacketed bullets, the rifle just hated that powder, even though it seemed to be a match made in heaven.
Which leads me to this current train of thought................
WHY?!?!?!
That's all. I just want to know why, when everything else looked so good, did this powder choice fail?
I have measurements on every blessed part of this rifle including what seems to be an accurate way to predict barrel harmonics, as well as case volume, speed, rate of twist, you name it! I even have pretty accurate pressure curves for given powders. What is there left to be measured? The only thing that I am truly taking on faith is chamber pressure.
If I can take a known performer and predict where the sweet spot is, why can I not first predict the known performer itself?
This is something I am going to be chasing as time permits. Someday I intend to get an Ohler shooting lab to go along with Quickload, but in the meantime, I am trying to educate myself as much as possible.

[Rocky Raab]

Oh contrare. Very little of what we do is much more than an educated guess. Some of it is pretty well educated and not much of a guess, but it's a surprisingly small slice of the whole avocado.

Talk to a genuine degree-bearing lab ballistician very much and you will soon come to the amazing conclusion that he's very aware of how darn little he really knows. Many of them will flat-out admit that while we may be able to say which propellants may be suitable for a given use, nobody can say which will prove to be the best. The reason they have to do so much testing is simply because they canNOT exactly predict what the results will be.

And if they can't, I double-dog guarantee you none of us can.

[MBTcustom]

Talk to a genuine degree-bearing lab ballistician very much and you will soon come to the amazing conclusion that he's very aware of how darn little he really knows. Many of them will flat-out admit that while we may be able to say which propellants may be suitable for a given use, nobody can say which will prove to be the best. The reason they have to do so much testing is simply because they canNOT exactly predict what the results will be.

Is that a fact? Have you talked to such a person?
(I'm not challenging you in any way, but you didn't actually say that you had spoken to a lab ballistician.)
While I agree that there is much in this sport that is taken on faith, I would also contest that much of it boils down to cold hard science, and I have never found a better resource for finding that info than right here on castboolits.gunloads.com
Just look at the Quest thread.
There is science a-plenty that has yet to be discovered. A large part of turning magic into science is finding a way to take measurements and then finding a way to use that information. Unfortunately, the folks who have the ability to measure, seem to not have the ability to make use of that information, and if they do, they are sworn to secrecy for liability reasons.
I am not trying to say that somebody out there has the ability to predict which powders are right for which guns (although I wouldn't be surprised). However, I do want to know how close they can get, and how they get there, that's all.
I have the ability to make testing equipment to determine the exact burn rate of each lot of powder. I have associates that can put that information into a database that will make use of it for comparison.
That's why I want to know. If I can get some equipment together, how close can I get?
I like the idea well enough, that I am not going to give up on it until somebody convinces me that it is absolutely an exercise in futility, but I'm not going to go all out unless I am totally convinced that I can get my moneys worth of education from it (other than "oh gee that was dumb as snake mittens! won't do that again!")

[smokeywolf]

Tim, have you taken this so-called ideal load of IMR 4198 and loaded identical cartridges with the exception of boolit hardness? Boolit hardness is going to influence barrel harmonics. coefficient of friction, and, you already know where I'm going with this.
Never having used Quickload I'm not aware if it allows input of BHN criteria.

smokeywolf

[Rocky Raab]

Yes, mr goodsteel, I have spoken with quite a few lab techs and ballisticians at length. (And I'm answering as you asked it, politely and non-contentiously.) In my work as a handloading writer, I have been extremely lucky to mine the brains of some very educated folks in this field, including Dr Helmut Broemel the ballistician/scientist who developed Quickload. While I am far too mathematically challenged to grasp the science of what they tell me, a few things are clear even to me. And one of them is that none of them would be willing to make a prediction of the "best" powder/load for a given component combination in an individual gun.

If it were possible for them to do so, reloading manuals would have only one or two powders and charges for each cartridge and bullet. Instead, there are a dozen or more powders at five or six charge levels per powder. Why? Because they can't predict how a given gun will perform with ANY of those choices.

[MBTcustom]

Boolit hardness is going to influence barrel harmonics. coefficient of friction, and, you already know where I'm going with this.
Never having used Quickload I'm not aware if it allows input of BHN criteria.

It does indeed allow for that variable. Its one of the things that should be tuned, but that is hard to do without Pressure Trace, or Ohler. The only two variables that you have to kind of feel your way through are powder burn speed and bullet hardness. I set the powder burn speed with jacketed bullets, and then I only have to tweak the boolit hardness when I switch projectiles.

Rockyraab, I meant no affront to you. I was honestly asking if you spoke to these people in person because you did not say it in your original post.
So, you actually got to speak to Dr Helmut Broemel? That must have been an experience! I could certainly bend that fellers ear for a second or two! Like I said, I think he's onto something, and I want to use this program a lot. I'm just still getting my head around what is possible.
So, again, how do they narrow the field of options? divide the list of possible powders into sorta kinda fast, sorta kinda smedium, and sorta kinda slow and start shooting? OK if you say so.
Would you venture a guess as to why (if not how) the IMR4198 did so terribly?
I set up the burn rate, and barrel time exactly like I did the other powders, so what I got should have been the best that powder could give me (or close to it).
I just wonder why it failed that's all.
You know what? it just hit me that I should just call some of these folks and get my answers strait up. Heck the Remington powder manufacturing plant is about an hour from the house. I'll just find out who the top dog is, and what beer he likes.:drinks:

[Rocky Raab]

No affront taken, my friend. Helmut is stereotypically German: detail is everything, and the more complex he can make something, the better he thinks it is. QuickLoad is a perfect example of that. He's also a bit hard to understand sometimes, because he assumes everybody thinks in quadratic equations and logarithms. (I sure as hell don't!)

Guys doing reloading manuals are incredibly pressed for time. They do nothing but handload, shoot and record results every hour of every shift, every day. And it can STILL take them years to work up loads for even a fraction of the cartridges and bullets in a manual. (Less than half of them are worked up new for each edition, sometimes only a third. Some near-obsolete rounds can go a decade or more without having a re-test shot fired.) So they have to do some pretty rigorous pruning of powders to try. Newest suitable powders are tops on the list, followed by powders that have been re-formulated, and lastly, old favorites. If there's time (and page space) they might try a powder or two just a bit too fast or too slow but that's about all they can squeeze in. Picking the "suitable" powders is about half science (Powley equations and programs like QuickLoad help) and half intuition based on experience.

As to your 4198 experience, it is a genuine puzzler. But I'd lean towards the "dwell time" and/or harmonics theories postulated by others up above. Oddly, there are also some primers and powders that simply don't "hit it off well" together. Whether it is the primer's flame temperature, gas volume, solid content, pressure rise curve, or chemical makeup of the plume - or the powder's deterrent type and amount, physical shape, flash suppressant, or position within the case - sometimes one powder just won't ignite or burn as smoothly as another with a given primer.

One way to test if that might be what's happening is to switch to (or from) a Federal primer and shoot a test series. Of the two general types of primer compound, Federal uses "basic" and everybody else uses "normal" primer chemistry. (It's based on the pH value.) One or the other can make a notable difference in how the charge ignites. Really.

[MBTcustom]

Hmmm, I never gave much thought into primers. I only shoot federal because they are shiny, and the boxes are bigger, and they are more expensive. (just kidding! I like them because they are softer)
I will dig up some "normal???" primers and give em a try.
Thanks for the help and tips. Thanks to everybody for your patience also!

[bearcove]

All I can gather is some powders work best is certain cases. It gives you a starting point. I wouldn't be likely to try 4198 in a 358 cause it seems to work best in straight walled cases.

BUT, I am just making an assumtion based on my limited experience and what I hear and read from others.

If you compare the 350 Rem Mag and the 35 Whelen they have basically the same case volume but different shape. What one likes seems to have little to do with what the other likes.

That's why I start with what works for others. Too many variables to waste my limited time and resources going off the beaten path. Well most the time. LOL!

[MBTcustom]

If you compare the 350 Rem Mag and the 35 Whelen they have basically the same case volume but different shape. What one likes seems to have little to do with what the other likes.
That is actually a very good point. Crazy stuff!
I should have known that this was going to be one of those questions that has no answer.
Curses!
Sometimes I wish I could go back and discover the miracle of proper fit again. My kingdom for a lightbulb moment!
You ever notice they get fewer and further between? Its like each gestalt takes twice as long as the one before it. Now I am gathering a list of questions to which there is no answer.

[Hamish]

"that the one difference that 4198 had over 3031 and W748 (two proven performers in this caliber) was that it came up to pressure much quicker than all of the traditional loads for this cartridge."

In my (admittedly limited) experience, 4198 has consistently performed poorly in relation to 3031.

If there is one thing that (I think) I have learned here, it is that the slower a load comes to peak pressure, the better. What I have taken from my wanderings here is that the "perfect" load, theoretically, will reach peak pressure and finish "burning" just prior to the Boolit exiting the bore.

One measly variable to consider: When a projectile is shoved down the bore, the projectile wants to stay at rest and therefore tries to impart spin to the barrel, ie, the bullet/boolit stays still and the rifle tries to spin around the bores axis.

Then start factoring in the variables of the distance from the center of the bore to the outside diameter of the barrel and what are you going to do now? There are 50 or 60 other things to consider in the equation too.

My own personal Double Naught Mathmespaztical Theory of the Whole Ball of Everything:

Everything can be dealt with by using the Bell Curve Rule. ITake any caliber of cartridge and consider a particular twist rate and a projected rate of speed and you will have to use a projectile in a particular range of weights that will correspond to a bell curve, those weights in the middle of that range being the most applicable and having the best expected outcome.

If you apply the BCR to your load using 4198, then you are using a variable that is out on the edge of the Bell Curve, on the high end, ergo, (If this cockamayme theory fits at all) you probably will not get a satisfactory result.

The BCR came to me in High School as I sat daydreaming for the umpteenth hour over the ballistics charts of every hunting cartridge then known to man, when in a supernova of understanding it became clear that ALL ballistics must obey the Bell Curve, and that NO cartridge could violate the brick wall of being able to shoot point blank further than about 300 yards.

Later when I started working in an archery shop, it was right in the middle of the war between mass versus speed. At the end of a whole lot of time and experimentation and study, it was again clear that even though the projectile speed was reduced by a factor of 10 compared to firearms, The BCR still was the ruling law of the Universe.

The only difference with bows versus guns is the fact that there are a drastically reduced set of variables to deal with concerning power curves and length and weight, which made it a sight easier to pick out components. But then Tim already knows this, being a traditional shooter.

I'm like Tim, *somewhere*, *someone* has done the research, but that doesn't mean we'll ever see it.

[Hamish]

You ever notice they get fewer and further between? Its like each gestalt takes twice as long as the one before it.

It's really only because as you go along, you're looking for the big answer to bigger questions than before.

When you are three, the flash of brilliance is that fire is hot and cookies are good.

We don't get too many easy ones any more.:bigsmyl2:

[Reloader06]

Rocky,

Could you expand abit on the "basic" and "normal" primers. This sounds very interesting.

Matt

[Flinchrock]

Rocky,

Could you expand abit on the "basic" and "normal" primers. This sounds very interesting.

Matt



Yeah,,it does.

[Rocky Raab]

First, Hamish, you have stumbled into the secret closet of understanding. In ballistics (as in so many other things) you are better off in the middle of the road than in either ditch.

Now to primer chemistry: There are two ways to formulate the common lead styphnate primer compound. One way is simpler and results in a compound that has a "normal" pH value. The other way is more complex (and a bit more dangerous) and results in a compound that has a pH that is more "basic." The basic flavor has the main advantage of being a bit easier to set off - and so primers made with it are more sensitive. That makes them usable in guns with weaker firing systems, among other advantages. The fired characteristics of basic primers is also a bit different. Gas volume, flame temp, peak pressure, and the amount of incandescent solids can vary as compared to "normal" compound. Those things can significantly alter how the powder ignites, obviously.

Long ago, Federal chose to go with "basic" priming, but all the others (WW, Rem, and CCI at least) went with the easier-to-manufacture "normal" style. The result is that Federal primers are a bit easier to ignite; that also makes them a bit more consistent, and is one reason why match shooters like them. They are also often rated as milder than other primers, due to those other characteristics noted above.

As a rough analogy, Federal primers versus other brands is a bit like charcoal versus gas: heat is heat, but the barbecue is different. That's not to say that one is better than another. But they are different.

[429421Cowboy]

Thank you Tim, for a very interesting thread! There is alot to digest here, but it gives me plenty to think about, and since i'm younger those:Bright idea: moments are simplier and more often[smilie=l:. But with the help of everybody here i am learning these things as well as i can.
Rocky, that is a very interesting bit of primer information i never had learned, i'll tuck that one away for later!

[Reloader06]

Rocky,

Very interesting. That does begin to explain a few things. I'll let my mind(such as it is) chew on that today during my nap. [smilie=6::popcorn:

[Ghost101]

Thank you Rocky Raab for explaining the different primer make up and how they work. I have a close friend who was a EOD in the Navy who now is a EOD for the BATFE. He told me what the two different methods of making the primers an the materials but it didn't really compute. You did.
I was telling him how I use to make primers for old pin fire and rimfire "blank rounds",years ago in SFX for the movies. He told me how they make them today.

Thanks again for the info

Ghost101

[44MAG#1]

If you have found IMR 4198 won't work it is time to move on. I've found that in my experience (43years) that there isn't anyone that can come real close to predicting anything about what a certain gun will do with a certain load.
While there have been loads that will do fairly well in some calibers in wide variety of guns that doesn't hold true in a large proportion.
If 3031 works don't fret over it and use it if it works.
Of course it does give one something to talk about and to post about.

[popper]

Tim, I have a similar situation with 2400 in 30/30. lite loads string vertically, normal (15+gr.) don't have much accuracy, I thought. My hypothesis is that the erratic ignition, burn and gun harmonics cause the problem (not talking predictable bbl whip). Nor am I speaking of S.E.E. I'm speaking of transient response of a solid. Hit a rod with an impulse and you get a specific harmonic response. Slow that down to a Gaussian and you get a different response. Add erratic burn and you superimpose several pulses, thus a different response. I do believe that gun makers 'tune' the gun to a particular 'load' or range of load for best performance. Looking at several pressure test curves, I see many have either a divit in the beginning pressure or a definite change in the pressure rate curve, exciting different harmonics in the bbl(which has a known harmonic response and is different for each gun). So, my conclusion is to choose a powder (and load) that gives the slowest rise and smoothest curve for most consistent performance. QL cannot provide this data, only Ohler type equipment can. In my uninformed opinion ( only looked at the tutorial program) QL can only guess at safe loads and give some fps guesses. Bedding, free-floating, etc. will only provide a gun with more consistent harmonics over time, temp. handling, etc. I did calculate the rotational energy in my 30/30 CB as only 5-10 ft-lb, compared to the 1500 forward energy. It does take a lot more energy to cram that CB into the rifling to get it to spin but is mostly longitudinal force to deform the CB - another pulse (slamming into the lands) to cause more harmonics. Hope this helps.

[felix]

Very good, Popper!

Where is Rocky? He quit, didn't he? ... felix

[youngda9]

Where is Rocky? He quit, didn't he? ... felix
Last Activity:07-09-2013 05:08 PM

Good thread ! Very thought provoking.

[dtknowles]

Tim

I just found this tread as it has been resurrected but maybe I have something for you to consider.

Assuming your were curious about predicting the accuracy (group size) a particular load will produce and never having used quickload. What does is request as far as the details of the firearm?

Computer programs can predict the load velocities pretty well and so can help select the powder that will produce the highest velocity for a given limit pressure.

Accuracy is such a much more complicated analysis task and some critical data points may not even be available. You did not describe the gun that you were testing but judging from the cartridge and the acceptable accuracy I assume it was not a benchrest rifle :-) Was the rifle barrel, straightened and/or stress relieved after machining to final contour. How was the rifling formed, forged, button, or cut. Was the barrel lapped.

The three most important factors in accurate shooting are the Shooter, the Gun and the Ammo in that order.

Shooter, myself I can cause about a quarter to half MOA variable in group size shooting typical hunting rifles off sandbags at 100 yards with little wind. With Varmint, target or benchrest rifles I can keep my contribution to inaccuracy to under a quarter MOA. I am just not top notch and don't get nearly enough practice.

Rifles, some guns are fussy and some shoot all ammo to about the same accuracy. There are two kinds of guns that are not very fussy. Varmint/target guns seem to shoot a lot of different ammo with a high degree of accuracy and many hunting rifles and GI battle rifles shoot almost all ammo with indifferent accuracy. Then there are the fussy guns that will shoot small groups but only with a pet load. I think it is pretty well documented what it takes to build a gun that will shoot small groups with about any ammo. A short, quality, heavy barrel. A stiff, blue printed action. Perfect bedding and free floated barrel. Anything else and you are likely to have a fussy rifle, you have indeterminate variables all over the place, to many unknown unknowns and unknowalbes, can't be analyzed.

Ammo, Bullets, Boolits, bullets. Without quality projectiles accuracy will be poor. Next most important are cases and case prep with my emphasis on bullet tension and alignment. Powder, primers and overall length are for tune. Fussy rifles are all about tune and as far as I can tell, tune is all about trial and error. For short range accuracy (under 200 yards) standard deviation of muzzle velocity does not have much effect on accuracy sometime low SD is not better (make no sense except that tune is overpowering consistency). How to achieve tune and what is it? Tune is primarily barrel harmonics and excitable modes. The powder that is predicted to best match the cases capacity might excite an adverse mode combination that will cause the bullet to leave the muzzle when the muzzle is whipping the fastest instead of closer to a node. Again tune is trial and error and as you learned your rifle might not be happy with a load that is considered optimal.

Tim

[MBTcustom]

Well, the reason I asked was that I had a powder that was too slow (3031) and I could go no faster than 2300FPS in my custom built, fiberglass stocked, Sako AV with a semi-heavy profile barrel, but I was getting consistent subMOA groups.
I wanted a powder that was a touch faster, so that I could get about 2500-2600 with the same fill. 4198 looked like the golden ticket, but instead of giving me similar accuracy at similar speeds, it blew my group into a shotgun blast.
I still don't understand why.

[dtknowles]

Well, the reason I asked was that I had a powder that was too slow (3031) and I could go no faster than 2300FPS in my custom built, fiberglass stocked, Sako AV with a semi-heavy profile barrel, but I was getting consistent subMOA groups.
I wanted a powder that was a touch faster, so that I could get about 2500-2600 with the same fill. 4198 looked like the golden ticket, but instead of giving me similar accuracy at similar speeds, it blew my group into a shotgun blast.
I still don't understand why.

Barrel harmonics, google it and find enough to read to keep you very busy. Some I think is too the point and some just background.

I suspect that you have a fussy rifle that needs a load to get it tuned or maybe it has a bedding problem. Either way I think you have a barrel harmonics issue. Did you build the rifle yourself? Is the barrel free floated? Have you tried forend pressure? You could have the barrel and action stress relieved by cryo treatment.

I am guessing you are looking to get 2500 fps with 200 gr bullets because I don't think you can get there with heavier bullets.

You could try Win 748 and see if you gun likes that plus you mentioned you might try different primers with 4198 and see if that makes a difference.

Tim

[MBTcustom]

The bedding was done with 10-110 1" in front of the recoil lug and I installed steel pillars in the stock.
I did build the rifle myself, and it has been a consistent good shooter with powders that it likes.
It shoots very well with jacketed bullets, but I don't shoot jacketed bullets. The point here is that this powder turned a 3/4" group into a 4" group without changing any other variable.
It's not the first time I found something a rifle doesn't like, and I understand the basic principles of HOW it is not working. What buggs me is the WHY, and I thought maybe somebody would have a sage answer.
Unfortunately, life is rarely that simple in areas where it matters is it?

[w5pv]

I don't have an answer but I have had better luck with 4831 than with 4895.4831 is a slower burning powder than 4895.

[felix]

The powder that is predicted to best match the cases capacity might excite an adverse mode combination that will cause the bullet to leave the muzzle when the muzzle is whipping the fastest instead of closer to a node. Tim

The barrel is traveling the fastest AT the "harmonic" nodes. Most literature suggest the nodes are defined as crossing points between max and min displacement. ... felix

[shdwlkr]

Tim
Just to add another variable if it hasn't already been mentioned is when you change lot number on the same powder. It can sometimes leave you with a hand full of hair and a bald spot.

I wonder if that is why I have more bald spots then hair on my head and more hair on my face then my head as I know enough not to pull facial hair it hurts real quick.

[Flinchrock]

Well, if someone ever figures this out, I think they will earn some money...

[popper]

Tim - as a G.S. you probably know most of this and I'll try to keep it simple. The fundamental (resonant/first)harmonic response of a cylinder is a function of the length, wall thickness & material strength. The first (radially) gives a vertical path, third is a cross path, 5th is a 6 petal star, etc. All of these occur in the barrel, at the same time, different places. Torque also gives axial modes. Stay with me here, pressure is energy. The rate of application of energy has 'frequency'. If the 'frequency' hits a harmonic, that harmonic response magnitude is greater. My hypothesis is that the higher harmonics generate wilder motion and fast burn powder hits those harmonics. Why does a rifle shoot jacketed well and cast not so well? Jacket is a better match to the bore and doesn't bang into the lands. our solution - seat into the lands. When that CB hits the lands & gets sized down, it puts more energy into the bbl. A big jump makes the 'hit' excite the higher harmonics. We hear a lot of talk about fast powder damaging the base and causing nose slump, I'm not convinced it is that big a problem. My 30/30 experiments with 2400 use the same alloy, same CB, same lube, same load. Accuracy is shotgun pattern, even with GCs. Same everything with slower powder gets me 1" @ 50, 200 fps slower. Same alloy, lube with slower powder gets me 2400+fps, MOA @ 100. The best bedding, best 'free-floating' can't solve the problem. I suspect bbl makers tune the design to get the 'normal/jacketed' load 'frequency' above the fundamental and we just excite the 5th with our poor powder/load choices. As a G.S., you would like to be able to 'guarantee' a build works with almost any load. My DPMS is tested with Rem 150 SPP and if I can't get the same accuracy I can send it back. QL is an internal ballistics calculator for the cartridge, not the barrel.

[MBTcustom]

Interesting stuff there popper. Lot's to think about.
I'm still figuring out QL's limitations and strengths. It's just a way to calculate barrel harmonics, but it makes no allowance for primer or twist rate. It assumes you have a pretty decent load to start with.