Powder Burn Rate

[GrampaMike]

I was looking at a powder burn rate chart and a question popped into my head (hurt a little bit).  If there is load data (same cartridge) for two different powders, say one is 60th on the chart and the other is 70th.  Does that mean that there is load data that would work with powders 61-69?  If this is a stupid question, it is OK to tell me so.

Thanks, Mike

[John Traveler]

GrandpaMike,

Your question is perfectly sensible.

Powder burn rates are done under controlled conditions inside of a "bomb calorimeter".  Measured powder charges are burned under confinement (like in a cartridge), and precise pressure, temperature, and heat energy measurements are made to find how much energy is given off.

Powder burn rates can actually change places when reloading variables (case, bullet, primer, seating depth, etc)  are changed.

So, when you look at a table of powder burning rates, the entries between high and low produces several other powders that will give you "safe" pressure within the cartridge and gun limitations.  

"Safe" does not mean "best".  The charge weight may be inefficient, or the velocity too low to be useful.  

It's these infinite combinations that allows experimentation for the best accuracy in a rifle!

HTH
John

[Castaway]

When looking at load data and burn rates, you can safely subsitute a slower powder grain recipe for a faster powder at a posted load.  In other words, if the load book says "X" grains of Bullseye, you can safely substitute the same grains of Unique and be below the pressure curve of the BE load

[Questor]

Grampa Mike:

Not really.   The charts really don't imply compatibility of powders applicable for a particular cartridge.  

The chart really just gives us a hint of what kinds of powders might be useful for a particular cartridge. For example, if you have load data for Bullseye powder in 45ACP, you can look at the chart and find that Clays, and Win 231 are similar in burn rate. This tells us that we may or may not find load data for those other two powders for 45ACP.

The real value of the chart is just to give insight about the spectrum of powders and what they are applicable for.  For example, using a heavy load of a fast burning pistol powder like Bullseye in a 30-06 will probably yield a serious explosion that destroys the gun, and perhaps the guy shooting it.  On the other hand, there are heavy magnum rifle cartridges like the 375H&H which use powders that are not classified as heavy magnum rifle powders.

The important thing is to leave ballistics to the pros.  We're just following the recipes they develop in the lab.  I can't understand where the notion of "the art of reloading" or "the sport of reloading" or "the science of reloading" came from.  There's very little creativity to it at all.  People who get "creative" with powder selection and application are the ones to beware of-- the shrapnel from their exploding guns could kill you.  If there is a convenient sound bite  to describe reloading, it should be "the discipline of reloading", because that's what it is.

As I gain more experience in shooting I am alarmed at how many reloaders take a cavalier attitude toward the basic safety rules.  For example, I now have a friend who loads shotgun shells as if they were rifle shells. He uses a powder charge for a specified load, but uses hulls and primers that were not published for that load.  

Anyone who has read the first paragraph of the Lyman shotshell loading guide, or any other shotshell loading guide will tell you that this is a gross violation of safety in shotshell loading. Yet I cannot convice him to change his ways. I won't go shooting with him.

GrampaMike, reloading is a pursuit worth studying. There's a lot of good information out there on how to make uniform ammo, more accurate ammo, loads that are good for hunting, loads for target shooting, etc. But it really takes a skeptical eye to evaluate the worth of load data or development technique.  The reloaders that I respect are unanimously cagey enough to cross-reference load data from multiple sources, aren't afraid to discard old load data when new data supersedes it, and buy multiple load manuals for cross referencing.  If something doesn't "smell right", they don't use the data.  

By the way if you're into rifles and accuracy, try the Precision Shooting reloading guide (cabelas sells it.) You will learn a lot about techniques of the benchrest and competitive rifle shooters. Fascinating reading, if you're a techno geek (even if you don't apply all of those techniques yourself.)

[Questor]

Here are a couple of cases that illustrate the details we need to follow:
1) When Win 296 is used in 44 magnum, it may be dangerous to use charges lighter than the specified minimum. The powder is made to operate when the case is loaded to near its capacity.

2) Seating a 9mm Parabellum bullet 1/10" deeper than specified can double the pressure.

The lore is replete with such examples.  Stick to the published recipes.

My own rule is that if I can't find the load in a major manual of recent publication, I will not use the load.  And there's no need to. The available data is quite thorough.  The only exceptions are cases where a bullet manufacturer specifies the load data, or the barrel manufacturer specifies the load data for a proprietary cartridge they have developed.

[GrampaMike]

Thanks for the replies...

Questor, I did not mean that I was going to "Invent" any load data.  I only thought it sounded logical that there would be load data somewhere for the powders between two listed powders.  Thanks for your concern though.  I am quite happy using published load data.  I follow all the "recipes" to the letter.  

I have noticed in two consecutive editions of same companys reloading manuals that the recipes have changed for the same cartridge.  Same powder, same bullet, but powder amounts are different.  Should I discard the older manuals data?  

Lately, I have been comparing load data from all my manuals, now have six.  They don't agree more often than they agree.  I have been using the highest "Starting" and the lowest "Maximum" as my loading range.  Even with this narrowing of load range, the combinations are endless enough for me.

I am going to visit my parents later this week in Michigan, there is a Cabela's store near them.  I will buy the "Precision Shooting Reloading Guide" as I am probably classified as a techno geek and want to learn what I can about reloading.

Again, I appreciate the time that everyone took to reply.

Mike.

[Questor]

I didn't think you would invent anything, but just bringing up the subject is a invitation for me to get on my pet soapbox.  

There is a relatively new method of measuring pressure that uses a piezoelectric sensor instead of lead or copper cylinders. It is considered superior to the old methods, but gives different results.  Also, powders do change over time.  Also, new discoveries are found to give improved performance.  

Consider Alliant 2400 powder. The recipes that were used by Elmer Keith 30 years ago would be excessive today.  Also, Speer recently revised its data for that powder for the 44 magnum. They found that they get lower pressures and higher velocities by using a standard primer instead of a magnum primer.

I am amazed at how many reloaders choose to use old data that uses is considered unsafe today. They reason that "it worked back then".

[Iowegan]

Back in the 60's I worked in a lab where we tested all types of firearms and factory ammunition. The "crusher" method was state-of-the-art then and was all we had to go by. It turns out that the crusher doesn't respond to peak pressure like the new piezo devices. We were getting more of an average pressure than a peak pressure.  The real damage to a gun's chamber is from peak pressure.  I keep my old manuals for reference but all my loading data comes from the new manuals. Not only have the testing methods changed, so have many of the powder formulas. ie: Unique. Also, don't confuse copper units of pressure (CUP) with pounds per square inch (PSI). They are no where near the same. Some call the lighter loads "lawyer loads" thinking that companies have gone more conservative to prevent law suits. The real reason is better data.

[GrampaMike]

I must admit the “Lawyer Loads” theory seems plausible to me, since I had no other facts/knowledge to go on.

I am sure my father is one of those “it worked back then” guys.  He has a couple of old manuals that were new when he bought them maybe 30 years ago, and he sees no good reason to change.  He says, “I have the same guns, same manuals and I buy the same components.”  He tells me that I try to make it to complicated.

Now thanks to you guys I have some valid arguments to use on him this weekend.  Printed off the posts to show him.  I am going to see what manuals that he has and buy him the current versions of them.

Mike

[Questor]

One diplomatic way of bringing up the topic is that powders have changed for the better. It's really worth taking a look at some of the new powders, like Hodgdon's Extreme line of powders.   There have been some definite changes for the better.

[Robert357]

It's not just lawyers that are causing loads to be changed!

Back in 2002, I wanted to try some powerful 357 Mag rounds in my Ruger Blackhawk.  So I bought a pound of Alliant 2400.  I carefully studied my various reloading manuals and then I studied the Alliant website for its suggested loads for a 158 grain jacketed hp bullet.  I figured that a jacketed 158 grain HP bullet should be a pretty safe and common loading for at 357 Mag.

WRONG!!!!!!!:shock:

I did a load work up.  Allaint on their webpage said the Max load was 15.2 grains.  I printed out the page so I would have it for my reloading notebook.  (I still have it and refer to it often as a reminder to be careful)

My work up started at 13.7 grains of Alliant 2400 powder and I had five rounds loaded for each charge of powder and increased them by 0.2 grain increments (i.e. 13.7, 13.9, 14.1, 14.3, 14.5, 14.7, 14.9, 15.1)  I knew that my highest (15.1) was slightly below the manufacturers listed maximum load (15.2).

I went out to the range and carefully shot and took notes on accuracy of my five round groups.  The 13.7 and 13.9 grain charges were pretty spectacular compared to what I was use to shooting.  

I started to get a concerned at about 14.3 grains due to the really flattened primers, but I kept going, since that was way lower than the manufacturers max load of 15.2.  At 14.7 grains on my first shot, I encountered a difficult extraction on my Ruger Blackhawk.  I thought about this and decided, that was enough and stopped.  I felt like I had chickened out, but part of my brain screamed STOP!

I went home and pulled the rest of my 14.7, 14.9, and 15.1 bullets and salvaged the bullets, powder, etc.  I then loaded up a bunch of 14.5 grain loads.  I then started to ask folks what gives?

Well within about two weeks the Alliant website quitely changed the max powder load for a 357 Mag with a 158 grain Jacketed HP bullet down to 14.0 grains!  

In retrospect, it was kind of scary to think what might have happened had I not done a load work up and stopped at signs of overpressure. I am also glad that Ruger builds such strong actions in their Blackhawks.  In fact, I now will no longer go past the FIRST sign of overpressure, which in my case was really flattened primers.

Therefore, it is not just attorneys that are changing the posted loads, it can be real live changes in the powder formulation by the manufacturer.  The lesson I learned is to always start low, do a load work-up, and always stop at any sign of overpressure!    

[Questor]

Robert357:

That's a perfect example of why cross-referencing loads is so important. Those editors don't catch everything.  Good story. I hope it didn't do any permanent damage to the gun. Sounds like your methodical approach kept you from running into real trouble.

[Robert357]

I stopped early enough.  No damage to the handgun, but you got to wonder what could have happened, especially if I had a cheap/weak 357 Magnum revolver.

I keep the printed Alliant max load information in my reloading notebook, just as a reminder to not start anywhere near max load on a load workup.  

I acutally think that the 200 rounds I loaded to 14.5 grains Alliant 2400 are safe to shoot in my Ruger (not in my Taurus), but if and when I shoot these self defense/hunting loads, I will through away the cases so they don't get reloaded.  They are in specially marked boxes ("Use only in Ruger Blackhawk-Self Defense/Hunting Loads") in the back of my gun safe.

Actually, I looked up loads prior to my putting powder in the cartridges in a Lyman Reloading manual, a Hodgdon Reloading Manual, Steve's Pages, and the Alliant website.  I know that Steve's Pages can be a bit "hot," but it is another reference point.  From what I saw the manufacturers 15.2 grains of Alliant 2400 didn't look unreasonable on paper.  

What I think really happened is that they reformulated things.  I was actually surprised that there wasn't a recall, but then again.......

[Iowegan]

When I started reloading over 40 years ago, I was convinced that loading "hot" was the way to go. As I got more seasoned, I found if my gun wasn't powerful enough, I should buy a bigger one rather than push the limits.

Working in the lab taught me a lot. I learned the "Optimize" concept that factory ammo makers use. They test a batch of guns chambered in a given cartridge. Through their tests, they find the best bullet weights, velocities, powders, primers, and seating depth to make the overall performance the best. That means the most power with the best accuracy and best terminal performance while keeping the chamber pressures at a safe level. Of course making one "load" to fit all guns is a tall order. When I reload, I try to match factory velocities and bullet weights. Then tinker with seating depth, crimp, bullet styles, and different powders to taylor the load to my gun.  Almost always, I'll find the optimum loads will be very close to factory ammo specs.

There are exceptions. For example, a Ruger SA in 45 Colt will be capable of much higher performance loads than a Colt or a Colt clone.  I have a 7X57 rifle and found factory ammo to be pretty weak. My loads are way higher in velocity but are still very accurate and show no signs of over pressure.  All my loads come from the newer reloading manuals.

[PaulS]

Burn rate charts are built using data gathered with the use of "Ballistic Bombs". These are  containment devices that are loaded with a specific weight of powder, closed up completely, brought to a "normal" temperature, and finally fired electrically. The transducers record pressure changes and temperature increases. Most powders behave differently in the confined but expandable space in a rifle or pistol. That is why the powder and bullet manufacturers test their load data. The design and construction of a bullet, the internal volume of a case and the dimensions of the chamber and barrel all modify the way a given charge of powder will behave in actual use. Use published data whenever you can and if you can't (a brand new wildcat) then use those powders that are the most flexible to work your loads up. Volume of the case and bore diameter will give a good idea of what powder is best for your application and how much to use. Then you can begin wiht a lowered charge and work your way up to find the load that provides you with accurate loads at the pressure that will keep the gun working well forever.

PaulS

[Donna]

Grampa Mike

If your a techno geek and have not visited my web site you and others may find it interesting and even fascinating.

http:/www.aeroballisticsonline.com

Enjoy
Donna :wink:

[GrampaMike]

Back from Michigan.  My Dad did listen to me this time.  He was using the first Sierra reloading book, dated 1972.  We went to Cabela's in Dundee Michigan, bought him the current Sierra book.  Compared the two books later, the loads he was using were within ranges of both books, but the books DID have different starting and Max loads.

Cabela's would not let me buy a shotgun because I am a resident of Virginia.  Where can I find what states that I can buy from?  I know this is off subject of this forum.

Donna I will check your site when I get a chance, thanks.

Mike

[Robert357]

GrandpaMike
 
Check the following link for a clue as to the "Limits to Interstate purchase & sale."
 
http://www.atf.gov/firearms/statelaws/24thedition/readyreftable.pdf
 
I believe that you were not in a contiguous state and so probably assumed to be a "gun runner" until proven innocent.  Hope you didn't miss out on a hunt by not being able to get a shotgun.

[GrampaMike]

Thanks for the link Robert...

Will look the sections sited....

Mike