Over the ranges of pressures usually encountered at the one inch position in shotguns the readings given by the two gauges are related by the equation;
P = 1.5L - 0.5 tons per sq inch X 2240
Where;
P = the maximum pressure (PSI) indicated by the piezoelectric gauge
L = the maximum pressure (TONS) indicated by the lead crusher gauge”
Excellent post Drew. I will just add a comment or so, note this formula only applies to
"The ranges of pressures usually encountered at the one-inch position in shotguns".
Also further note that Burrard stated this formula would not give an "Exact" conversion, but within the criteria given it was extremely Close & would not give a serious error.
Using "The Formula" a 3-ton LUP would convert to a 4 ton PSI. It should be extremely obvious that a gun safe with 4-ton PSI would not necessarily be safe with 4-ton LUP. Multiplying by 2240 (Long Ton) gives 3-ton = 6720 & 4-ton = 8960 or a 33% increase.
A 4-ton lup would convert to 5.5-ton psi or 12,320 psi. It should be obvious when comparing pressures it is imperative to stay within the same methods of measuring.
Note that none of this contradicts what Drew wrote, just putting in some actual figures. Even though a 3-ton LUP pressure converts to 4-ton psi, there is a world of difference between a 3-ton & 4-ton when Both are LUP. The conversion equates to a 33% increase in Reading, while the latter is an actual 33% increase in Pressure.
