Sources of load data

[leadchucker]

Please forgive the noob questions, but searches don't really turn up any answers to this.

One of the books I have read in preparing to try my hand at loading, "Metallic Cartridge Reloading," suggests that the powder maker is the prime source for load data. The author even goes so far as to advise only using load data that comes directly from the powder maker.

And yet several other highly respected loading manuals list loads that are not present in the powder maker's load data. There is even some conflicting data between respected sources sometime.

For example:

There is load data for only three 380 ACP bullets in the Winchester/Hodgdon load data for the use of W231.

There is load data for five 380 bullets in the 49th ed. Lyman Reloading Handbook for use with this powder.

Where does this extra load data come from?
And more important, what is the best criteria for judging whether data is reliable (read safe) or not?

[Jim243]

And more important, what is the best criteria for judging whether data is reliable (read safe) or not?

You are!! That is why we always say start low and work your way up. Lyman 49th is a good reference book because it is not specific to any one manufacturer. I use my books in this order.

1. Bullet manufacturer's information and load data. (it is specific to the bullet I will be using)

2. Powder manufacture's information and load data. (it is specific to the powder I will be using and I get as close to the same type and weight bullet)

3. When all else fails, I go to Lyman's and try to match the bullet type and weight as close as I can to the powder speed I will be using.

Start low and work up your loads and always check for over pressure signs.
Jim

[wncchester]

I've been doing this a looong time and have learned not to much care who provides the data, doing as Jim243 says - "start low, ..."etc - is the only safe way to go.

[Incognito]

My method so far has been to gather up all starting and maximum loads from as many legitimate sources as I can. Then I add them all up & divide them to determine the average minimum & maximum loads from the data gathered.

[Clark]

In 1958 Vernon Speer came to some of the same conclusions as I have about the irrelevance of absolute pressure measurement.
But while he measured the rim, I measure the extractor groove as a precursor to loose primer pockets in cartridges with deep extractor grooves.
While he reduced powder charges 6% for the manuals he published, I reduce by 3 ~4% for my personal use.

P.O. Ackley "Volume I Handbook for Shooters & Reloaders" 1962 Quotes Vernon Speer on page 148 and 149:

"There is a tremendous difference in the way different rifles handle pressure and it is entirely possible that a rifle used in one test was different in this respect than another one we used. We do not have a pressure gun in our laboratory, because it is in my opinion, backed up by quite a few years experience, as well as firing data from various laboratories pressure guns that data received from them is exceedingly unreliable. For a company such as Remington or Winchester having the same gun and operator comparable results to check on production problems are no doubt sufficiently accurate for the purpose for which they are used.

We use the head expansion method in determining the pressure at which a cartridge case was fired. It is our belief that the cartridge is the weakest link in the modern bolt action rifle. If the pressures at which the cartridge cases are fired do not exceed the elastic limit of the unsupported rim of the cartridge case, then we consider that the pressures are entirely usable, regardless of what they might be. We fire increased loads, increasing the charge at about a grain at time, checking the rim diameter of the cartridge case with sensitive measuring instruments, both before and after firing. If any measurable increase in the diameter of the rim of the case is noted, we consider that pressure excessive and reduce the charge about 6% and list it as a maximum load in our loading table. There is no reason why the handloader cannot use this same procedure himself and determine whether or not the loads he is using are safe and practical for use in his rifle.

In our laboratory we look for all signs of pressure such as sticky cases, tough extraction, flattened or cratered primers, as well as the rim expansion method noted above. Some cartridge cases are softer than others, notably Norma cases, and will not stand the higher pressure loadings possible in Remington and Winchester cases. This tends to bear out our contention that as long as the brass cartridge case is worked within the elastic range of the brass, then the pressure in the pounds per square inch, whatever it might be, is safe and practical for use in that particular cartridge. I hope I have been able to explain this pressure problem to your satisfaction.

Vernon D. Speer, February 6, 1958"

[Dr. Strangelove]

You can also call the powder company, they have never failed to give me a start and max load for any bullet I happen to use.

They all have 1-800 numbers.

[FrankenMauser]

Each company uses different test equipment, different barrels (or firearms), and prefers different components. Their data will differ from the data published by others.


As a general rule, I use data from the company that produces the bullet I am using. If possible, I'll cross-reference that data with the company that produces the powder I'm using. The basic reason for this, is just to double check charge weights and minimum OALs. Some of the more advanced reasons can include things like deciding on an appropriate primer for that particular powder and charge weight (magnum vs standard, Winchester vs CCI vs Remington, or even small rifle vs small pistol magnum).



In a 'worst case scenario', give Sierra a call. They advertise the following (in a few variations):

While we would like to have all of our callers shooting Sierra bullets, this service is not used to push Sierra. As our advertising states "our technicians will have the answer to your reloading questions, even if you're not using a Sierra Bullet".

The Bulletsmith slogan used to be, "Any bullet, Any powder, Any cartridge." I don't blame them for changing it. Keeping up with all the new powders, new cartridges, new bullets, and maintaining data for obsolete and 'standard' cartridges (with new, old, and updated components) can be quite a task.

[spacecoast]

www.reloadammo.com
www.handloads.com
www.accuratepowder.com
www.hodgdon.com
www.alliantpowder.com

Don't use a single source - make sure you cross-check and that it looks reasonable based upon loads for heavier and lighter bullets.

I have quite a bit of .380 data if that's what you are looking for, and about 5 different loads I have tested in my guns. Let me know what you are looking for, I've used Titegroup, AA#2 and Unique powder.