Stop Jawing About It and… Just Do It!

By Ron Robinson.

Recalling how excited I was to discover organized airgun competition and how quickly I jumped at the chance to enter my first silhouette match, it seems strange how many airgun enthusiasts procrastinate and/or are intimidated to enter their first silhouette or field-target competition. Perhaps it’s performance anxiety (fear of a poor showing), but many airgunners simply cannot seem to “pull the trigger” (so to speak) when it comes to entering their first match. Many are attracted enough to these airgun games to participate in on-line forums with posts and questions, yet are apparently repelled by some unexplained force.

While I can see why one might be hesitant to attempt such a demanding discipline as ten-meter competition, reactionary-targets like silhouettes and field-targets hardly lend themselves to structured venues or up-tight participants. And while I’ve heard field-target shooters referred to as “elitist”, truth is the only “elite” thing about them is their shooting skills.

After years of field-target and decades of airgun silhouette experience, I can state unequivocally that neither discipline attracts a pretentious following, and the term “discipline” is in fact a misnomer for either game. A much more accurate description than the “elitist” comment mentioned above was overheard from a spectator at a Texas State Silhouette Championship, “It’s a bunch ‘a grown men shooting BB guns at little metal animals!” How intimidating can that be?

To the silhouette and field-target-curious out there in Airgunland procrastinating their first competition out of whatever misguided fear one conjures to avoid discovering some of the best airgun fun to be had with like-minded individuals, I feel compelled to give one piece of advice.

"Try it... you'll like it!"


A pretty up-tight bunch - just look at those scowls!

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Keep Powerlets in Your Pocket, Gain 20fps Muzzle Velocity With Your QB78

Here's some test results that show why you should keep 12 Gram CO2 Powerlets in the pocket of your jeans before loading them into your QB78 family air rifle. Oh yes, and then wait for 3 minutes before beginning to shoot. It can make 20fps difference to muzzle velocity!

I made 10 tests, each time loading a QB78 air rifle with two full standard 12 Gram Powerlets. In every case, I had warmed the Powerlets in the pocket of my jeans for about 30 minutes beforehand.

The table below shows (from left):
1) The ambient (room) temperature.
2) The initial temperature of the gun before loading Powerlets.
3) The temperature of the gun immediately after the warm Powerlets were loaded.
4) The temperature of the gun immediately after piercing the Powerlets.
5) The temperature of the gun after waiting 3 minutes.

On average, the guns started at approximately room temperature - 67 or 68 degrees.

After running this test a few times, it occurred to me that I should be recording the temperature increase of the gun after I loaded the Powerlets that had been in my pocket. Duhhh...

So, we can see that the temperature of the gun rose by about 7 degrees F immediately after loading with the warm Powerlets.

Piercing the Powerlets caused the temperature of the gun to fall by 10 degrees. Gun temperature stabilized at about ambient temperature again after 3 minutes in ambient temperatures of 65 to 70 degrees F.

So, what do we learn from this data?
- Keep Powerlets warm before use.
- Wait for at least 3 minutes before starting to shoot your gun.

The reason for all this interest in gun temperature is that the muzzle velocity of QB78-family air rifles - like all CO2-powered guns including the Crosman 160 - changes with temperature. For the QB78, this change is 2fps per degree F. So we see that just piercing the Powerlets in your gun causes the temperature to fall by 10 degrees F. That represents a FALL in muzzle velocity of 20fps!

For those of us wanting the best performance from our Q78s, that 20fps makes a big difference, not just to muzzle velocity, but also to the point of impact.

Doubtless, the results would be different in higher ambient temperatures (and the differences less marked), but 70-ish has been about the best we have been able to manage in Up-State New York recently. Conversely, I would expect the effect to be more marked at lower ambient temperatures.

The gun temperature readings were made using the Archer Airguns Temperature Monitoring Kit for QB78.

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Spring Air Rifle Test Results - Stoeger X50 and QB57

As several folk sent emails saying they found previous "Gold Service" test targets interesting, here's a couple more that have just gone through the shop.

The first shows the test target for a .177 caliber Stoeger X50. Here we can see the excellent accuracy out of the box - if I do my part! - displayed by all the X50 guns I've tested so far. As with almost all of these guns, there was no dieseling at all and the Standard Deviation (muzzle velocity variation) is excellent for a brand-new springer.

The X50s shoot at approximately 1100fps with CPLs, giving 20+ ft/lbs of muzzle energy. The trigger pull weight on this Stoeger X50 was a little above average, most show less than 5lbs pull weight, but it still felt fine and gave predictable let-off.

By way of a comparison, we have a test target for a QB57 Deluxe in .22 caliber. As is Archer Airguns practice, the gun was tested with my trusty Leapers red dot scope.

Some QB57s can be very "wet" from the Shanghai factory and show considerable dieseling when first fired, but this one was nicely dry and gave outstanding figures of only 5.38 ft/sec over 10 shots. This is QB78 territory!

Trigger pull was very light, too, at only 3 lbs 3 oz. QB57 triggers have a long pull, but a little experience makes them quite predictable. And nearly 10ft/lb of muzzle energy in an accurate, controllable package is pretty good for such a compact air rifle that sells for less than $75.00 and has so few plastic parts.

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Don't try this with your QB78, folks.

Of course, you would never load two pellets into your QB78 air rifle, close the bolt and fire. But, oops! that’s exactly what I did recently when performing a Gold Service test on a QB78. My excuse is that I was distracted by a telephone call in between shots...

Anyhow, I had fired eight pellets with this .22 caliber QB78. The muzzle velocity was in the 500 - 510fps range for these shots and then - all of a sudden - there was a 290fps reading. WTF?????

So, I looked at the target and you can see the results below. I had double-loaded this QB78 and the gun fired both pellets at once. The result was the 290fps reading from the Chrony and the impact of two pellets about 1 1/2-inches below the impact point of the main group.


So, that’s what happens when you double load a QB78 family air rifle and fire it by mistake...

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There's no free Lunch! QB78 family muzzle velocity, temperature and CO2 use.

I’ve always been interested in the effect of temperature on CO2-powered air rifles, such as the QB78. But, until I developed the Archer Airguns QB78 Temperature Monitoring Kit - based on an idea from local Rochester NY airgun enthusiast Doug Wall - I didn’t have a way to measure what happens as we fire our air rifles and use the CO2.

Now, I’m going to apologize immediately for the part hand-drawn, part Excel graph, but I think it shows a behavior of QB78 air rifles that has not been recorded before.

This shows how the temperature of the Main Tube (and therefore the CO2) falls with the number of shots fired until - I believe - all the liquid CO2 is used. After that, as the gun starts running on CO2 gas only, the temperature of the gun rises again until the gas is exhausted and the muzzle velocity collapses.

It also shows how increasing muzzle velocity is purchased through the use of increased amounts of CO2. We can see how improving the gas flow causes the temperature of the gun to decline faster under constant shooting rates and how the liquid CO2 is used faster to buy the increased muzzle velocity.

This graph takes three tests on the same .177 cal QB78 air rifle and compares the temperature of the Main Tube (measured by the Archer Airguns QB78 Temperature Monitoring Kit) in three configurations.

First, I tested a standard factory gun.
Second, I modified this gun with a replacement breech seal from the Archer Airguns 2X Seal Kit.
Third, I fitted an Archer Airguns XP Tune Kit to the gun.

In each case, the gun was charged with two full 12g Powerlets and fired every 30 seconds until the muzzle velocity dropped to around 300fps.

Click the graph to enlarge for easier viewing.

As you can see, the ambient temperature increased slowly in the range as I undertook the tests - must have been all that hot air I was generating!

So, the factory spec gun was tested at 66 degrees F ambient temperature. The first shot attained a mere 536fps (this was a “slow” gun) at a Main Tube temperature of 62 degrees F. The temperature dropped steadily until it reached a minimum of 56 degrees F after about 80 shots and the muzzle velocity had declined to 503fps. Then it increased again to 62 degrees F as the muzzle velocity dropped away to 315fps after about 100 shots.

By comparison, the same QB78 fitted with a replacement breech seal from our Archer Airguns “2X’ Seal Kit, started at 64 degrees F with a muzzle velocity of 604fps, dropping to 504fps after about 55 shots and finishing down at 300fps after about 80 shots.

Fitting the Archer Airguns “XP” Tune Kit, increased the muzzle velocity of shot one to 692fps (an increase of 156fps over the factory configuration!) at 66 degrees F, but the liquid CO2 was used after only about 35 shots at 644fps. The 300fps point was reached after about 60 shots.

So, at a constant shooting rate, the QB78 cools faster with increasing gas use (ie higher muzzle velocity). The temperature of the gun increases again after all the liquid CO2 is used.

The practical application of this data is that tuned guns may need to be shot more slowly to maintain their muzzle velocity - and therefore vertical point of impact on the target. The standard factory configuration gives more consistent muzzle velocity over a much larger number of shots and the gun cools much more slowly. Lower muzzle velocity is better for paper-punching accuracy.

Below, the Archer Airguns QB78 Temperature Monitoring Kit reading 73 degrees F.

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