New load starting point

[jefats]

Say you want to use a powder that is not listed for the caliber and bullet in any of the manuals but is close on the burning rate charts to others you've used in the past with published data in the manuals. How does one go about determining a safe charge as a starting point with said powder?

Example: the H/IMR powders with the same numbering are not always offered in same caliber/bullet data. It's usually one or the other. Then there are the "oldies" like NORMA powders which are not generally listed anymore but supplies are still to be had and used say, in the BR cartridges 22, 6, 30 etc. but no data is available.

So, how does one begin safely?

Thanks for helping an old dog learn new tricks.

 

[eric32]

i think some more information is need such as

what caliber are you shooting?

Bullet weight?

what powder are you trying to use?

 

[Lapua40X]

If you're sure that one of the many reloading manuals currently in publication doesn't have the data you need, there are sites from which you can purchase vintage reloading manuals. Let your search engine (vintage reloading manuals) to the work for you.
Unless I had the equipment to produce accurate CUP (copper units of pressure) data for experimental loads for which there was not published load data, I wouldn't start playing around with unknowns.
Some years ago, during a training session where a .38 cal. revolver had a double or greater charge of Bullseye in the case, I was standing next to the shooter at the firing line when the gun exploded. The uppermost cylinder chamber blew out and separated the top strap from the frame. We never did find the top strap or the missing piece of the cylinder. Luckily those pieces didn't hit anyone.
But, if you've just gotta do it:
http://www.ktgunsmith.com/straingauge.htm
http://www.chuckhawks.com/pressure_measurement.htm

 

[CatShooter]

Say you want to use a powder that is not listed for the caliber and bullet in any of the manuals but is close on the burning rate charts to others you've used in the past with published data in the manuals. How does one go about determining a safe charge as a starting point with said powder?

Example: the H/IMR powders with the same numbering are not always offered in same caliber/bullet data. It's usually one or the other. Then there are the "oldies" like NORMA powders which are not generally listed anymore but supplies are still to be had and used say, in the BR cartridges 22, 6, 30 etc. but no data is available.

So, how does one begin safely?

Thanks for helping an old dog learn new tricks.

You interpolate.

When powders are close, you build a data matrix around the powder you want to use - since (these days) there are so many powders that you have to chose from, it is not rocket science (but is probable over the head of the average reloader )

Take loading data for "X" and other close powders with bullet weights, or cases that you can get bulk data with, and plot them so you can establish a position for "X" with known loads, between known powders. The more data you can get, the more better.

Then plot the other powders WITH the case and bullet weight you want data for, and plot them out on 1/10" graph paper. Then draw a parallel line for your "X" powder.

Drop 10% and work up - looking or the usual suspects.

I do this stuff for a living, and very often have this as a real problem - I finely broke down and bought a pressure gun (for insurance purposes) and it confirmed what I was doing all along.


.

 

[Erik Cortina]

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