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Many years ago I had the pleasure of working with the late Homer Powley. The attached chart is based on his "Powley Computer for Handloaders", that can be purchased from "Hutton Ranch, PO Box 45236, Boise, Id, 93711". The computer is slide rule type and gives the optimum powder for 100% case capicity. It works ony for the IMR type powders since they all develop the same amount pressure/per grain weight, but with a different burning rate.
How to use....fill a fired unprimed case to the bullet seating depth with water..weigh..pour all the water out and weigh again. Subtract this from the weight with water and you have the weight of water. Multypy this by .859 ( averagr density ofIMR powders) and devide that by the bullet weight in grains...This gives you the C(harge)W(eight)R(atio). Find the intersecting line between the Sectional Density of your bullet and the CWR. This gives your optimum type of powser and the Weight of water times the LD of the powder gives you the amount of powder. All this is based on 44,000/45,000 psi. If your multiply the weight of powder times 1.05 you get an increase in velocity of 5%, but an increase inpresure of 10%.
Best Regards from the Hammock....James
 

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Sorry Boys..I've tried 3 or 4 times to upload the chart, but it just will not go.It's a file called Powley1.jpg, but when I try it locks up everything. The only choice is..If you are really interested send me you snail-mail address and i will send you a copy.
Best Regards from the Hammock....James
 

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Mr. Gates!

Try again on Saturday evening... by then I'll be able to have Alex reset the image upload limits.   They are set to a 200K max in an effort to preserve bandwidth.   We'll bump them up a bit so charts and information like this can be posted... sorry for the shortsightedness on our part!

Please try again after we up the limits!

God Bless,

Marshall
 

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Discussion Starter #4
HERE'S THE CHART..It's a file called "powley.jpg..it can be saved and printed..when you print it tell the printer to "scale to fit page"...I hadto resize it to fit the meg allowed. This is how the factory ballistic boys start a new load and then refine.



<a href="http://www.beartoothbullets.com/upload/powley.JPG" target='_blank'>http://www.beartoothbullets.com/upload/powley.JPG</a>
Best Regards from the hammock....James
 

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Mr. Gates!

Once again I thank you for great information!  With the print feature on our new forum, everyone can enjoy the information!

I don't know if you have the formulas for Mr. Powleys calculations using this information.   But if you do, we might be able to write the script to make it function on our Ballistician's Corner along with all the other goodies that are already there... don't know, but worth a shot perhaps!

My hat's off to you sir! And many thanks from us all!

God Bless,

Marshall
 

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Discussion Starter #6
Dear Marshall and Friends of the Forum..Homer Powley was a fine Christian Gentleman, that was light years ahead of his peers. I was fortunate to know him and have him share with me "some" of his work. Over the years he established methods for the various conpany ballistic people to test and develop their products. I used his methods in developing the 7.62x47mm International, which is used in Europe as a target round. The purpose of his "Computer for Handloaders" was to give to the advanced handloader a method to develop his own loads and understand better basic relationships of..CWR(powder charge weight to bullet weight), SD(sectional density of the bullet) and ER (expansion ratio-the number of times the volume of the cartridge case in gas can expand in a specific length barrel). He set up his computer for a 44,000\45,000 psi level and them explained how to take that psi up to SAMMI specs for the carteidge. He selected the 44,000/45,000 psi in order to cover the strength of most actions (ex..The Swedish 96 and the stronger lever guns).
In my first post..I stated that the IMR powders produce the same pressure per grain, BUT AT A DIFFERENT BURNING RATE! This burning rate is most important in overcoming the inertia of the bullet...the heavier the bullet the slower the burning rates must be. Unlike other powder factories, DuPont built into their powders these rates. An example of this would be the following.....30-06-58 grs IMR 4350-165 gr [email protected]'/"...For the same pressure and velocity..105% of IMR 4831 @ 61 grs, for "d"(nonexist for sale) 95% @ 55 grs and IMR 3031 @ 52 grs. So we see the 5% change in burning rates/pressure/powder weights.
So...The concept that a full case of some kind of powder/proper burning rate for the sectional density of the bullet is ideal.
The chart shows, in graphics, what the computer does to pick a powder for a known bullet weight and caliber to give 100% loading density in the hull...but that's not all the COMPUTER does..By knowing your caliber/weight (SD) and the length of barrel/caliber by volume(expansion ratio)-the computer will calculate the velocity within 5% ( due the variations in barrel, etc.)
Another factor...To calculate the powder needed for a reduced velocity with a known bullet caliber/weight, it will pick the powder and weight...ex- I want to push Marshall's 173 gr 30 cal. bullet at 2200'/".. Knowing the ER of my 22" barrel and the SD of the bullet.I feed it in and get 36 grs of IMR 4064. To build up my bulk(in grains of powder) I multiply by 115% and get 41 grs of IMR 4350 or (105% of IMR 4350)44 grs of IMR 4831.
Play with the chart awhile and maybe buy his computer...It looks kinda like a sliderule. Any direct questions at [email protected]
Best Regards from the Hammock.....James
 
 

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James,

This is an old thread but seemed like a good place to ask the question.
While discussing the Powlry Computer with a friend I asked myself: "When did powder burn rate charts appea?"

Looking around I do not see powder burn rate charts in pre-WW II magazines or even in the late 1950's.
The first actual chart I came come up with is the ladder chart in Ribert Hutton's article for the 3rd Edition of the Handlaoders Digest. The article is Boom! Bang! Crack! and is about the Powley Computer for Handloaders, powder selction and an overview of available powders and a discussion of the new powders handloaders hoped to see introduced.

Propellent powders were described and discussed very differently in the 1940's through the '60's than they are today.
I figured that you or Nick would have an idea of when the powder burn rate charts began to appear.


 
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