Drum and bar type measures
In operation, every time a powder measure reaches the end of its stroke it slams into the end stop, which causes the whole measure to shake. When a powder measure cuts a kernel of powder, it also shakes. This shaking settles the powder in the reservoir, changing the pack density. The pack density change is related to how hard the stops are hit or how hard it was to shear the powder The next time the drum or slide bar metering chamber comes under the reservoir tube it gets a charge of powder dropped into it that is varying in density, driven by the weight of the powder in the reservoir, which is constantly changing. These are the main reasons for the inaccuracies in these designs.
The Quick Measure Solution
First we had design a system that would eliminate the pack density problem, the constantly changing weight in the powder reservoir and one that would not shear a kernel of powder. The new valve system in the Quick Measure has two vertical precision brass tubes, one stationary and one movable. These tubes each have a hole machined in the side. When the movable tube is raised to the top of the stroke the holes line up and the powder flows horizontally into a separate metering chamber. Because we move the powder into a separate metering chamber the weight of the powder in the reservoir has absolutely no effect on the powder in the metering chamber. One problem solved. When the powder starts to flow the varying pack density created by cutting kernels and hitting top and bottom stops is immediately alleviated. Second problem solved. The movable tube has an angled brass plug at the top which will causes the last kernel of powder to be forced up into the reservoir instead of being cut. This system can not cut a kernel of powder. Third problem solved.
To further promote accuracy we machine the bottom of the reservoir at a special angle that optimizes powder flow. This part is polished and anodized. Charging directly into the cartridge case We have designed a funnel that has an operating button installed for use when dumping powder directly into the cartridge case. Just hold the funnel in one hand and the quick measure in the other. Place the charge tube on the operating button in the funnel and press down. Hesitate for one to two seconds, allowing the metering chamber to fill, then lift the measure to dispense the charge directly into the cartridge case. This action is possible because the new valve operates so easily. 100 charges can be dispensed in about 4 minutes.
Interchangeable charge tubes
We have designed the system with adjustable interchangeable charge tubes. Each charge tube has it's own adjusting screw. Once set, they can be locked with a liquid thread locker. These tubes can then be interchanged, without tools, in about two seconds. This eliminates the time consuming adjusting procedure when you need to switch to a previously adjusted load. The Setting Gauge We have also designed a Setting Gauge for keeping track of the adjusting screw position making it easy to return a charge tube adjusting screw to a previously determined setting. This can also be used for load adjustment.
We have solved many problems that have plagued the other powder dispensing machines for years. You will not find a more accurate measure than the Quick Measure. As with all measures you will have to practice your technique to get consistent charges. A characteristic of extruded powders is that they will settle a little differently in the metering chamber each time. This is minimized in the Quick Measure by opening the valve quickly. This will promote a more consistent powder flow into the metering chamber resulting in more consistent charges. We heard from one bench rest shooter, a mechanical engineer, who claims it will never get any better than the Quick Measure because we are the only people that have solved all of the powder dispensing problems.
JOHNSON DESIGN SPECIALTIES
4607 West Elderberry Avenue, Spokane, Washington 99208, United States
Made in USA
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