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22 November, 2009

More on QB78 Family Main Tube and Tube Cap Lengths

In order to know if your QB78-family air rifle has a short or long Main Tube, you need to measure it. Length of the old, short main tubes is about 14 7/8-inches, length of the new, longer tubes is about 15 3/8-inches. (They're actually made to metric measurements, of course). Long tubes will only work with long tube caps, short ones with short tube caps, due to the fixed length of Powerlets. All other parts are the same.

I spoke to the factory folk about this change when I was in Shanghai, recently. They developed the modification to make it easier to change the tube cap O ring. It applies to all Powerlet-driven QB78 family models, including the AR2078 and AR2078A.

Here's a photo of the old and new Tube Caps.

But some long tubes do not have the gas release hole at the threaded end of the tube - this can cause the tube cap to fly off of the gun if there's residual gas pressure when removing. This is not usually a problem if you know about it, but be aware! I was assured that all future production will include this gas relief hole.

As with most production changes in most factories where the old part is not defective in design, the change from short to long tubes/caps was cut in over time. For example, the most recent cases of guns that arrived with us last month have mostly long tubes, but some - in the same case and number sequence - have short tubes. So, the serial numbers I've posted for the change (08686XXX) should be seen as a guide to about where it began. Measurement is the only sure way to know.

This post amplifies some information posted earlier about the short and long tube caps that match these tube lengths.


07 November, 2009

Duct Seal - The Ideal Pellet Trap Material

Duct Seal is the ideal material to use in airgun pellet traps. It is cheap, long-lasting, effective and quiet. That's why we specify and supply it for the Archer Airguns "Silent" Pellet Traps.

But sometimes folk are not readily convinced and ask for proof of it's ability for pellet trap use.

So, here's a photograph of a test I made. It shows the penetration of a heavy (14.5 Grain), pointed RWS Superpoint pellet, fired "point blank" (from 6 inches) into a 1-inch thick block of Duct Seal. The pellet was fired by a QB36-2 air rifle at 800 fps, the muzzle energy being approximately 20 ft/lbs.

As you can see, the pellet penetrated just under 7/8-inch into the Duct Seal. To allow for the effect of multiple impacts, we recommend depths of Duct Seal in our "Silent" Pellet Traps as follows:

For .177 wadcutters Muzzle Velocity Duct Seal Depth
500fps 1 inch
900fps 2 inches
1200fps 4 inches
Add 50% to all depths for pointed pellets

For .22 wadcutters Muzzle Velocity Duct Seal Depth
500fps 1 inch
700fps 2 inches
1000 fps 4 inches
Add 50% to all depths for pointed pellets

And, if that's not good enough for you, we also offer 3/8-inch sheet steel plates to put behind the Duct Seal as a final insurance policy against penetration by pellets.

Our second photograph shows my long-serving Premium "Silent" Pellet Trap, used for Gold Service tests on air rifles. As you can see, the DuctSeal shows impacts from many pellets - this is still the same Duct Seal I've been using for over 5 years! Also you can see how target debris and spent pellets collect in the base of the trap, instead of bouncing out, as they tend to do with other pellet traps.


06 November, 2009

The Leapers Tactical Rail Adapter - A Very Uesful Item.

The Leapers Tactical Rail Adapter is a versatile accessory for many air rifles. It clamps to standard airgun rails and allows Weaver mount scopes and sights to be fitted securely. It's also an ideal way to increase the scope rail length found on some Chinese air rifles, providing a 4-inch Weaver rail and allowing for better scope positioning.

Here is is on a QB78 breech.

And here it is in use on my customised QB57.


05 November, 2009

It's Seasonal Sale Time at Archer Airguns!

If you haven't visited our retail web store yet, now is a good time to do so. There's a wide range of sale bargains available in all parts of the site.

Have fun :-)


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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