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Re: Took my 1884 out for the first time
Posted by Larry Gibson on Thursday, 23 January 2014, at 10:20 p.m., in response to Re: Took my 1884 out for the first time, posted by phatcyclist on Thursday, 23 January 2014, at 9:30 p.m.
A strain gauge is permanently fixed to the barrel over the center of the chamber. Measurements on barrel material and dimensions under the gauge are input into the program. On firing the case expands and pushes on the chamber causing a "strain". The instrument measures the strain and then converts to psi. The instrument feeds the data into a laptop. The M43 also measures instrumental velocity with screens a measured distance from the muzzle and converts that to muzzle velocity and energy and provides a ballistic program to 500 yards. I can put another set of screens in front of the down range target (out to 100 yards/meters) where it measures the time of flight and computes the actual BC for each shot. A lot of other data is also provided including a time/pressure trace for each shot.
Dr Oehler ran a test where he used a C.U. P. test fixture and affixed 2 different strain gauges, 2 different peizo-transducers and a case mouth gas transducer to the same test barrel. Thus he could get 7 different measurements of pressure for the same shot. The strain gauges measured the psi as accurately as the peizo-transducers which proved better than the C.U.P. method of pressure measurement. That's why most all the industry is/has converted to transducers for load development and strain gauges for continual testing in commercial made firearms.
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