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03 November, 2010

QB78 HDD test with XP Tune Kit

Here's one of the final test targets from our extensive QB78 HDD test program.

It shows a test of the HDD using just one 12g Powerlet with a 59mm (average length) spring and a very light hammer weight of 53g (which was achieved by cutting off the end of a 57g factory hammer).

The .22 caliber QB78 was fired once every 60 seconds and I was NOT AIMING at the target. The gun was on a rifle rest, but I was concentrating on exact shot timing, not the point of aim!

Anyhow, you can see that, even with just one Powerlet, 30 unaimed shots went into a ragged 3/4-inch hole before the point of impact seriously dropped as the gas was used.

Ambient temperature in the range was 65 degrees F and the gun temperature in this test held fairly constant at 61 - 62 degrees F over the first 30 shots.

Average muzzle velocity for shots 1 - 10 was 589 fps. For shots 11-20 it was 572fps and shots 21-30 averaged 522fps. The muzzle velocity did not drop below 500fps until shot 29 (still 502fps at shot 28), but then dropped rapidly.

Holding nearly 30 shots before a significant muzzle velocity and point of impact decline for this HDD plus XP Tune Kit combination with only ONE POWERLET compares to previous tests of the XP Tune Kit without HDD but with TWO POWERLETS where about 35 "good" shots were achieved.

This was one of many tests where the HDD designed by Steve_in_NC proved it's ability to provide over 40% more muzzle energy from the QB78 than without and how this translates into many more useable shots per fill of CO2.


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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