What’s inside your airgun barrel? Yes, I know that may sound like a stupid question. However it’s very rare to see photographs taken of the inside of an airgun barrel – until now, that is!
This post shows the first photographic results of some investigations inside airgun barrels using a borescope. I think they are very interesting and hope that you will agree. There will be more to come, too…
What Is A Borescope?
Well, it’s a device that enables you to look inside a barrel. The clever part is that the borescope provides both a bright source of light inside that very narrow tube, plus the ability to see – or photograph – the results.
In fact, the HAM Team has been experimenting with borescopes inside airgun barrels for a while now. HAM PCP Tester Doug Rogers bought a superb Hawkeye model from the Gradient Lens Corporation some time ago. Here it is.
Doug’s borescope is used for visual observation only. It gives a superb image, but I have failed to record any decent quality photographs through it. And yes, I’ve really, really tried!
Of course there is a camera system available for Hawkeye borescopes, but sadly it’s priced beyond the HAM budget.
So I have moved to an alternative solution. The Teslong NTG500 Borescope is a dedicated “photograph-producing” model. It’s waaaaaay lower-priced than Doug’s Hawkeye borescope. But I have been able to produce photographs from it. Some of these are what you see here.
In use, the Teslong borescope is operated from the control unit. This also displays the image on a screen and records it, should you wish to take a photograph.
Using A Borescope Inside An Airgun Barrel
Both the Hawkeye and Teslong borescopes have the same two modes of looking inside an airgun barrel. These are a “straight ahead” view and a “right angle” view. I have been using both.
The “straight ahead” view is produced using a lens that looks straight out of the end of the borescope. That lens is surrounded by very bright LEDs – as you can see in this photograph.
The result is a photograph looking something like this.
Here we are looking straight ahead down the bore of an airgun barrel. That light blob at the end is the breech end of the tube. You can clearly see the multiple grooves and lands as they spiral slowly down the barrel.
Note that any borescope has a very limited “depth of field”. It’s inevitable for optical reasons. This means that only a small distance ahead of the lens will be sharp. Too far, or too close and the image is out-of-focus.
Again, that’s easily seen in the photograph above.
Note that the bright highlights, deep shadows and perspective effect generated by the borescope tend to make the bore look MUCH rougher than it really is in “straight ahead” photographs.
The second way of using a borescope is to fit a mirror over the end. This mirror is set at 45 degrees to the optical axis and so gives a view exactly at right angles to the bore. Here it is.
Now the resulting photograph looks like this.
You can see the mirror and how it’s view is at 90 degrees to the bore. Some of the “straight ahead” view can be seen around the mirror area for confirmation. It’s particularly sharp at the top right of this photograph.
Also the bore is seen to be very smooth, in comparison to the “straight ahead” view above.
So what air rifle was used to generate these first borescope photographs inside an airgun barrel? It’s the BSA R-10 SE that we currently have in-house for review. But the bore shown in the photograph of the Teslong unit looks very different and is actually from another air rifle.
Stand by. There’s a lot more to come…
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Teslong NTG500 Borescope
The post What’s Inside Your Airgun Barrel? First Borescope Results appeared first on Hard Air Magazine.
. How bout something for .17 . You'd think the tech is available by now .. ijdk...
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