# LUP-to-PSI?



## song_dog_slammer (Dec 26, 2000)

IS there a converion factor or non-linear table that will allow me to convert LUP? into PSI? What the heck does LUP stand for. HELP!


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## Shoveler (Mar 17, 2001)

song_dog_slammer

I have been reloading for only a couple of years now but this is what I have. From Speer,Lead Crusher: A pure lead cylinder used in a pressure gun for obtaining lead units of pressure (L.U.P. or lup). Formerly used to test low-pressure cartridges such as shotshells, this system is now obsolete in the US. I do not know of any conversion or logarithm for going from LUP to PSI. Maybe someone else will post that data.

Shoveler


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## Mr. 16 gauge (Jan 26, 2000)

Song-Dog;
Back before electricity, Alfred Nobel (the guy who invented dynamite), came up with a way to measure the pressure in the chamber of a gun. Prior to his device, the only way to check out if a load was dangerous was to just keep packing powder down the barrel until it exploded. (How would you like THAT job! )
His device (called a "crusher") basically looked like a cannon, and it had a hole drilled in the breach at a right angle to the bore. a "piston" was inserted into this hole, and a copper or lead cylinder placed between the piston and an "anvil". The gun was fired, and since Newtonian physics states that the force will be equal in all directions, the piston was pushed up and distorted the lead or copper cylinder. Technicians would then measure the amount of distortion and using tables supplied by the manufacturer, would calculate the psi of the load.
When strain gauges came out (after electricity was discovered), some scientific eggheads decided that there should be a way to distinguish between those measurements made by gauges and those using the crusher. To distinguish the two, they decided that "L.U.P" or "C.U.P" should be used to distinguish those using the crusher from those using strain gauges (PSI). Essentially, they are measuring the same number, just doing it in different ways. the problem with the crusher system was that it could be anywhere from 5 to 20% off, and only measure the "peak" pressure, as opposed to the strain gauge, which could give an accurate picture of the whole detonation. I checked some of my different reloading manuals, and where the components are the same, there is little, if any difference between psi and lup, which is probably why there is no conversion table available.
Does this help you, or have I confused the heck out of you?


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## song_dog_slammer (Dec 26, 2000)

Thanx Guys, Song Dog says" When in doubt, ask those who know." Anyway I did the same component comparison and it appeared as though the units a interchangable.


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