"If you look in older reloading manuals (or even some newer ones), you'll find the pressure of various reloading formulas expressed in LUP (or lead units of pressure). Those are measurements derived from the old lead crusher system, which the British still use. There's no formula to convert crusher values to transducer values, but an acceptable "ballpark" conversion is: LUP + 1,000 = psi. (Which you can also reverse, if for some reason you want to convert from psi to LUP.) If you add 1,000 to the figures Miller gives above, you come pretty close--especially to service pressure."
I agree to most of what Larry was saying except that in this case do not use the 1,000 conversion from LUPs to PSI, there is no correlation of the two. When Lyman first used the crusher method they called it psi, but found out it wasn't in psi, and eventually this same pressure value began to be listed as l.u.p.
This syestem was used for decades and more and more people wanted to know what the psi was instead of lups. Plus the lup system with the lead crusher was very time consuming and labor intense.
A new system was developed in the 60's using electronic equipment to actually measure in psi. No more aligning lance holes up exactly with the piston in the chamber.
There is no universal difference between the two, in fact some loads are 9,000 lups develop 11,500 psi. On some 12 ga reloads the difference is only 300-1,400 psi. Many of the loads using lead shot developed in the lup system reamin at an accetable level of pressure in the psi system. Now with steel shot the comparison is way higher between the two.
In Lymans 4th Edition of Shotshell Relaoding they give both L.U.P. and P.S.I., in the new edtion they only list psi.
So do not compare psi listings with lup listngs.
If you shoot 16 ga and reload and shoot 70-100+ year old guns there is no better place to learn than on the 16 ga. Reloaders site. They give you information on 2 1/2"-2 3/4" low pressure reloads for our old guns to shoot safely. It cost money, a one time deal, but the information is outstanding and all the loads are proven.
Last edited by JDW; 04/01/07 09:16 AM.
