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.

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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.

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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.

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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 :-)

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A Quick Performance Test of the New QB58 Air Rifle

Here's the results of a brief "real world" performance test of the new QB58 air rifle. This gun is very similar mechanically to the QB57, but the QB58 in a fixed stock format instead of the "take down" and bullpup configuration of the QB57.


I pulled 3 QB58s of each caliber out of the rack - making no selection - and measured the muzzle velocities and weights of each.

The .22 caliber QB58s are all quite dry - much like the QB36-2s I tested a few days ago (see the following post). The .177s, however, had much more oil on them from manufacture and there was a fair amount of dieseling. The muzzle velocities should be understood in that light. As before, these are obviously not "broken in" numbers.

In .22 caliber the QB58s ran an average of close to 600fps with "The Peak" wadcutters. Maximum muzzle velocity recorded was 609fps, minimum was 576fps. At 13.86 Grains weight and an average muzzle velocity of 600fps, this makes the muzzle energy around 11 ft/lbs. The manufacturer's official spec for the QB58 is 580fps, so these guns were performing fairly well above that claim.

As the.177 caliber models were dieseling, there was a greater spread of muzzle velocities. The maximum recorded individual shot was 792fps, the slowest came in at 669fps. Average muzzle velocity would be in the 730 fps range with "The Peak" wadcutters pellets. At 8.6 Grains average weight, the muzzle energy is around 9.5 ft/lbs. The factory spec is 750 fps, so this time the manufacturer's numbers may be a little optimistic, but probably not by very much.

As for weights, the .22s came in between 7lbs 2 oz and 7 lbs 4oz each. The .177s were in the range from 7 lbs 6 oz to 7lbs 7oz.

So, that's what I'm finding with these new QB58s. The finish looks good, cocking is not too heavy, the anti-beartrap features seem to work well and the triggers and safeties worked fine. Although I was not specifically shooting for accuracy, the groups on my test target suggest that the QB58 is accurate and not particularly hold-sensitive, either.

As with the QB36-2s I reviewed a few days ago, I'd say these are fine air rifles for the modest price being asked.

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