Finally! The 100% Compatible HDD Kit for QB78 Family Air Rifles.

As of this month, the QB78 HDD has been shipping with a CNC-manufactured hammer pin that's designed by Steve_in_NC specifically to provide guaranteed compatibility with the HDD itself.

This removes the issue found in our extensive HDD testing program that about 10% of factory hammer pins were too large in diameter to fit the HDD.

To be clear, this means that the HDD fits the QB78, QB78 Deluxe, QB79, AR2078, AR2078A, AR2079A and all clones and other versions of these models such as the Tech Force TF78 and TF79 series marketed in the US and the SMK XS78 etc marketed in the UK.

The HDD itself remains the same and still provides an outstanding improvement of greater than 40% in muzzle energy for the same gas use.

Also, the HDD kit is now shipping with an improved breech seal that makes assembly much easier. This is a square-section hard rubber ring that locates perfectly in the QB78 Main Tube aperture and stays in place while the HDD is assembled. It compresses when the breech screws are tightened-down and gives an excellent seal. There's no deformation and airflow restriction as is experienced with the factory seal. And, unlike the hard plastic breech seals we've previously supplied, they are both more precise in thickness and re-usable.

You can find the HDD on our site.

The new breech seal is also shipping in our "XP" Tune Kits.

As usual, we've done extensive testing on this new breech seal on a wide range of QB78-family air rifles and it works faultlessly. A few of you will already have received this breech seal in HDD and "XP" Tune Kits as we started the change-over to the new style part. But 6 January - was the official availability date for these improvements to our products.