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Old February 22, 2013, 05:22 PM   #1
SL1
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Issues matching Nosler .357 Mag data with QL

I have been spending some time trying to match velocity vs charge weight data in various manuals using the QuickLOAD program.

Some of the data in the latest Nosler manual (#6) for the .357 Magnum cartridge looks suspect. I tried calling Nosler and speaking to a "tech" but found that he had no interest what-so-ever in considering that some of their data might not be correct or might not be published correctly.

So, I am putting it out here to see what others think.

Here is a graph of the data provided for the 158 grain JHP:



As you can see, the data for all of the faster powders, except SR-4756, show a reasonable velocity increase with increasing powder charge, while the slowest powders do not. (SR-4756 is not quite as bad as the slow powders, but also looks weird.)

Matching the fast powders that I have in the QuickLOAD data base (only AA #5 and #7) showes fairly decent agreement with the data when just using the default values in QuickLOAD:



However, trying the same thing with the two slow powders does not:



The lowest dotted lines are the QuickLOAD results using the default values. The middle dotted lines are the QuickLOAD values with the case capacity reduced to produce the SAAMI max pressure for the top charge of 2400 powder, with the same capacity used for W-296. The upper dotted line is with the default case capacity, but the Burning Rate Factor for each powder has been increased to produce the SAAMI max pressure for the top charge.

What is obvious in these graphs is that the slopes of the 2400 and 296 plot lines are MUCH different for 2400 and 296 than for the faster powders, and that QuickLOAD matches the faster powders pretty well, but no adjustment of the QuickLOAD parameters comes close to matching the slope of the slow powders.

My guess at the cause of this situation is that the Nosler ballistician's chronograph might have been reading the shock waves from the fireballs produced with the slow powders rather than the passages of the bullets.

The data for these powders is a follows. (It was shot with an 8.3" H&S Precision barrel):

2400 11.3 grains 1480 fps
11.8 grains 1500 fps
12.3 grains 1520 fps

296 13.8 grains 1520 fps
14.3 grains 1530 fps
14.8 grains 1540 fps

Another thought is that these charges seem rather light for these powders in this cartridge with this weight bullet. Perhaps the powders are not burning well.

What do others think?

SL1
Attached Images
File Type: jpg Nosler 357 Mag data.jpg (20.9 KB, 27 views)
File Type: jpg QL match fast p.jpg (20.8 KB, 24 views)
File Type: jpg QL match slow p.jpg (25.3 KB, 29 views)

Last edited by SL1; February 23, 2013 at 09:50 AM.
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Old February 22, 2013, 06:36 PM   #2
buck460XVR
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Quote:
My guess at the cause of this situation is that the Nosler ballistician's chronograph might have been reading the shock waves from the fireballs produced with the slow powders rather than the passages of the bullets.

My guess would be that the techs at Nosler know more about reading a chrono than to make an obvious error like that. I think test barrels and the difference in the resulting pressures created by them would be more plausible. I shoot a lot of Nosler 158 grainers over H110/W296 and have chronoed them myself. The results shown in your Quickload example is close to what I get from my 5 and 6 inch revolvers. What Nosler shows is a tad less than what I get from my 20'' carbine with similar charges.
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Old February 22, 2013, 08:14 PM   #3
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Buck,

Are you saying that you can subtract a grain of powder from your max 296 loads and only lose 20 fps in velocity from your revolver?

That is what got my attention.

Speer seems to think that you lose 94 fps by subtracting 1.5 grains, and Hornady seems to think that you would lose 50 fps by subtracting 0.8 grains. Those are both equal to 63 fps per grain of 296, both from 6" revolver barrels.

QuickLOAD showes a loss of 108 fps per grain of 296 for the 8.3" barrel.

But, remember, a revolver with a "six-inch barrel" is really more like a 7.6" barrel when you add in the cylinder length. So, the real difference between the test barrel data and the revolver data is the presence of the cylinder gap and the forcing cone.

Speer made a pressure test apparatus for a revovler many years ago, when piezo transducers were relatively new. It showed that the pressure curves were much different in the revolver, with higher peaks and more rapidly reducing pressure after the peak. At least, that was true with the bullets that they manufactured at that time. They found that slightly reducing bullet diameter changed that. Then, they also changed to thick-plated bullets ("Unicor" and "Gold Dot") instead of cup-and-core. But, Hornady bullets are still cup-and-core.

So, I am not seeing anything like this Nosler data from anybody else. That is why I am asking about your personal chrono data, particularly the slope of the line in fps change per grain change.

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Old February 22, 2013, 08:44 PM   #4
eldermike
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I think the 8.3 inch test barrel is the issue. My Nosler number 3 has the same data as you listed. SPEER tested with a 6 inch security six. Speer number 11 lists 296 at 17.8 max for 158 grain. It lists 15.9 max for 2400. But again a revolver and a closed breech test barrel are not the same test.

Just so you know I would never load a max load for anything unless I had worked up to it. Reloading data from any single source is worthless in my experience.
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Old February 22, 2013, 09:01 PM   #5
SL1
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Mike,

I don't think that the Nosler data can be explained by the test barrel.

Contender barrels typically produce velocities similar to test barrels of similar length, and they usually match QuickLOAD pretty well. For example, the latest Speer manual has some 10" Contender barrel data for their 180 grain bullet, and its slope is 89 fps per grain of 296. Nosler's data for their 180 grain Partition showes a slope of 136 fps per grain of 296 out of the same barrel that produced the 20 fps per grain slope with their 158 grain bullet.

So, the slope of the Nosler 158 grain bullet data seems weird, even when compared to the slope of their own 180 grain bullet, using the same barrel and presumably the same lots of powder, primer and cases.

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Old February 22, 2013, 09:01 PM   #6
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If it helps out any I was told that QL really isn't the best for straight wall cases.I am pretty sure it was someone from here that told me that.
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Old February 22, 2013, 09:18 PM   #7
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I can tell you from experience that velocity increases are not linear with respect to linear changes to powder weights. And the curves are not predictable.
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Old February 22, 2013, 09:37 PM   #8
SL1
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Mike,

You wrote "velocity increases are not linear with respect to linear changes to powder weights."

That has not been my experience with a chronograph. At least until I am pushing max pressures pretty hard, the load work-up seems pretty linear. And, that is what the manauls typically show, as well.

What I usually have trouble with is the SLOPE of the line, not the linearity.

And, sometimes different manuals show different slopes for the same powders behind the same weight bullets. Of course, the bullets have different designs, were shot from different guns, and used different lots of primers, powder and cases. They may have even been shot with different measurement systems (CUP vs psi) and of course used different apparatus in the different laboratories.

But, when you get down to it, why in the world would anybody add a grain of powder to get an additional 20 fps?

This is the lowest slope value I have encountered anywhere, so that is what I am questioning. There are a lot of uncontrolled variables that people can hide behind if the don't want to see a problem. But, I think any objective look at this data should raise a question and warrant some attention. I know I would certainly take another look if it were MY data. And, that is just because I want to understand it and use it for myself. If I were considering publishing it for others to see, I would at least want to have an explanation when somebody questioned it.

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Old February 22, 2013, 10:10 PM   #9
eldermike
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I hear you. But understand that when you qualify an absolute with "AT LEAST UNTIL" its no longer true. There are plenty of errors in loading manuals. Perhaps your research will make them better in the future.
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Old February 23, 2013, 12:09 PM   #10
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Quote:
Buck,

Are you saying that you can subtract a grain of powder from your max 296 loads and only lose 20 fps in velocity from your revolver?

I dunno. I do know there becomes a point where I can add .5 of a grain and get no increase in velocity or very little.

Quote:
That is why I am asking about your personal chrono data, particularly the slope of the line in fps change per grain change.
That info is mostly in my head and is filed in that area where things of little importance is stored. While many need to know and document every little detail of their reloads, to me velocity is not high up there on priority. My Chrono gets used to make sure my ammo velocity is in a range that is appropriate for the useage and to make sure it does not exceed published velocity. If my loads are close to factory in velocity and/or published velocities, and accurate, exact velocity and deviation is of little importance to me. Many times I see velocities published that are above and beyond those published in other manuals. Not an unusual occurrence. One reason I always try to use at least three references when working up a load. If one of the three or four references is obviously different than the others, it raises scrutiny, but I don't automatically assume it is wrong and feel the need to call the company and tell them they made a mistake and what they are doing wrong. Maybe if I was an engineer or chemist with a specialty in working with modern ammunition propellants, but not being an average Joe Reloader. I have loaded thousands of Nosler .38 caliber 158gr JHPs over H110/W296. I do not have their manual, but the info you posted from there is in line with Hornady and Speer manuals for similar bullets. Those two are also quite conservative compared to Hodgdon and Lyman for similar bullets in .357 mag. My loads lie somewhere in the middle, where their accuracy has proven the best in my guns. Ain't got a clue what the exact velocity is. I know my load is safe and accurate....as I believe the load Nosler gives is.
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Old February 23, 2013, 08:16 PM   #11
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Buck,

The differences between you and me are partly that I am an engineer with a lot of experience in making numerical models and dealing with models made by other people. It is a (good) habit to do "reality checks" on models and the data that are used with them. Otherwise, you can mislead yourself to the point that your faith in a model causes dangerous situations.

So, when dealing with highly different data from various manuals for the same powders in the same cartridge, I want to get a better understanding of what MY chronograph data can tell me about MY gun, particularly inferring the pressures that my loads are probably developing.

QuickLOAD is the best tool I have found so far for doing that. But, it is far from perfect. So, before relying on it, I try to get it to reproduce the manual data that applies to the bullet I am using. Sometimes I can't adjust it to do that. When that happens, it is not always clear whether it is the program or the manual that is in error. In this particular case, I am pretty sure that it is the manual, rather than the program. My reasons for that, as stated in the various posts above, have less to do with my faith in QuickLOAD and more to do with the discrepencies between the Nosler manual and all other pressure-tested data that I can find for the same powder in the same cartridge with very similar bullets.

Another difference between you and me is that I work-up my loads with a chronograph whenever I am going for a high-pressure load. And, I take notes on what charge weights produce what velocities. That is the best way I have for telling when I am getting close to a SAAMI or other pressure limit. I also try to get QuickLOAD to reproduce the work-up results BEFORE I get to the top charge weights.

In many of my cartridges, that is not so important. But, is several it is. For example, I have a .30 Herret barrel for an old Contender. Most of the load data for the .30 Herret was produced before folks realized what pressures stretch those old-style Contender frames. And, there is an amazing variation in both the hardware and the data. So, I exercise a lot of care when working up those loads. The .357 Magnum is much the same. My state wrote its deer hunting laws to allow the .357 Magnum in revolvers with 6" or greater length barrels, but it specified muzzle energy instead of the cartridge and ammo. With the change in the SAAMI pressure limits for the cartridge, reaching the legal limit with that cartridge is now a real push. (The introduction of Buffalo Bore ammo has finally solved that problem if you don't mind shooting expensive factory ammo.)

So, my interest in understanding manual data and QuickLOAD tuning comes from an interest in achieving performance safely. I can understand others not sharing those interests, as I hope others will understand that these are MY interests, which are not unique in the handloading community.

"Proving somebody wrong" is not a goal of mine. But, often that is the way somebody takes it when I question their data or models. And, that is the way it was when I was paid to do it in other disciplines, so I am used to it. It is surprising just how many errors there are in data and in models, and how often they cause models to be substantially wrong. Even the models that I produced myself. Another set of eyes is usually a good thing so long as the goal is to improve the product rather than just to inflate somebody's ego. Usually, after a rough start, the modellers or data producers come to realize that what I am doing actually helps them, and then they WANT to colaborate with me.

My intent with this thread is to see if there are others on this forum who can help me get a better handle on why the subject Nosler data looks so strange. Members who are not interested in that need not pay attention to this thread.

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