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20 December, 2012

QB78 HDD Performance Data and Review

Apologies for the shortage of blog posts this month, but - as you can imagine - we've been extremely busy fulfilling customer orders...

There is, however, some new and interesting data on the QB78 Hammer Debounce Device - the HDD - that has been generated by the designer - Steve_in_NC. Steve used a sound recording software program to produce a graph of the noise generated by firing a QB78. And he did this when firing the gun both with and without having an HDD fitted.

The graphs are shown below. The basic way to understand these graphs is that the X-axis (across the screen) indicates time, while the Y axis (up and down) measures the amplitude, or strength, of the noise.

A comparison of the "with HDD " and "without HDD" charts shows that with the HDD fitted the hammer strikes the valve just once. Without the HDD, the hammer hits the valve repeatedly - you can actually see this in the charts as the three big blocks of up-and-down blue lines.

First, the trace from firing a QB78 WITHOUT a HDD installed.

When the QB78 was fired with a HDD installed, the chart looks very different. There's only one big block of blue lines - the hammer hitting the valve only once. It's a pretty dead blow.

These charts give a very technical description of the HDD actually working. Thanks Steve!

But what does that mean in practice?

The following graph shows the results of some shooting tests I undertook on a QB78 fitted with the HDD.

As you can see, the QB78 tested held a muzzle velocity above 495fps for 74 - YES SEVENTY-FOUR! - shots. This compares to the 50 - 55 shots that can be produced by a gun in factory (non HDD-fitted) condition. That means that the point of impact is held for many more shots with an HDD-fitted gun than without. The result is better accuracy and a considerably greater number of "good" shots per fill!

And yes, the QB78 HDD works with all QB78 type air rifles.


About This Blog

This blog shares information, ideas and knowledge about air rifles. It compliments the information Stephen publishes on the Archer Airguns website, on YouTube and the Chinese Airgun Forum.

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