Does the Model 43 measure true pressure?

Yes. It actually measures the strain (or stretch) on the outside of the barrel over the chamber. The strain is directly related to the chamber pressure by the inside and outside diameters of the barrel at the point of gage attachment. This provides an accurate indication of pressure in your gun; the same ammo can give a different pressure if fired in a different gun.

The only way to get a better measurement of the chamber pressure requires drilling a hole through the chamber wall into the case.

Does the measured pressure correspond to actual PSI or copper units pressure?

The pressure measured by the Model 43 corresponds closely to actual PSI readings. Copper crusher readings are so suspect that we hesitate to compare.

Does the Model 43 measure SAAMI pressures?

The Model 43 is not intended to measure pressures in accordance with SAAMI standards. SAAMI standards require the use of qualified test barrels, reference ammunition, proper calibration, and adherence to exacting procedures. Oehler Systems 82 and 83 are made for SAAMI applications. Comparing the Model 43 to our industrial systems is like comparing an accurate varmint rifle to a rugged African double. They each perform their expected functions very well, but they are not interchangeable.

Can the Model 43 be used indoors?

The Model 43 is intended for use outdoors under sunlight. Trying to use the Model 43 indoors with artificial lights can be frustrating. This is especially true in an electrically noisy environment near electric motors and solenoids.

 

Is a special computer required?

Originally the software was written in 1991 for DOS and requires a DOS compatible computer. It will run in the DOS window of Windows® 3.x or Windows® 95.

A Windows® version was completed a few years ago that runs under Windows® 95, 98, ME, and NT 4.x. There's also a version available for Windows® 2000. See the support page for more details.

How accurate is the acoustic target?

For bullets with velocity at the target of greater than 1500 fps, accuracy of the acoustic target is better than 0.1 inch.

How accurate is the ballistic coefficient?

Ballistic coefficients are very difficult to measure. You can expect accuracy better than 3% if you use a muzzle screen spacing of 8 feet, a range of at least 300 feet measured to an accuracy of ± 0.2 foot, and pay close attention to temperature and atmospheric pressure.

Will the strain gages work with all guns?

No. The strain gage must be glued to the barrel directly over the chamber area. Top-break shotguns and Contenders are ideal. We urge shotshell testers to dedicate an inexpensive top-break gun with an open choke as a test gun. Pistol shooters should use a Contender for pressure tests. Bolt action rifles work fine if the shoulder of the case extends at least half-inch beyond the receiver. (Short cases such as PPCs and Hornets are best tested in a Contender barrel.)