My home made bore-scope.

I made my borescope three or four years ago for a particular job. Iíd bought a new rifle and although it shot well enough it was a devil of a job to clean and I could feel, as I cleaned it, that the barrel was very rough inside. Not having access to a borescope I decided to try and cobble something together myself and take a look. Here's the result.

I started by buying a cheap bore viewer from Cabelas in the USA for around £30. These are marketed as "Clearview affordable borescope" Now these viewers are very basic, they have no light source and no right-angle mirror so I knew I would need to modify it somewhat to be of any use.



Basic bore viewer






The first problem was to try and arrange some sort of angled mirror, it would need to be adjustable for length to allow proper focusing of the eye piece and also small enough to fit inside my 6.5mm barrel. At a local model shop I was able to find some thin walled brass tube that was a sliding fit over the existing viewer tube and still fit inside the barrel.

The next job was to sort out the mirror. I needed a wooded shaft that would fit inside the outer brass tube; this would give me something to fix the mirror to at the correct angle. I found a suitable size wooden rod in the shaft of an artistís paint brush and proceeded to cut it across at 45 degrees. 

Outer tube showing mirror and LED










I located some thin mirror in a make-up set from the local pound shop; it was around 1.5mm thick. I broke it up and selected a chip about half a centimetre square and superglued it to the angled face on the wood dowel, now came the slow process of grinding the mirror down to the correct size to enable it to slide into the outer brass tube, I used a Dremmel type tool   with a diamond disc for this job. I also used the Dremmel with the cutting disc to make a small opening in the brass outer tube to allow the mirror to ďseeĒ out.

I assembled the parts and with a little fine tuning I found the system was working perfectly, I was getting a good right-angled view and being able, by sliding the outer brass tube, to set the coarse focus. Fine focus is adjusted by turning the eyepiece.


Now I needed a lighting system; LEDís were the obvious answer so I found a 2mm white light led.   Positioning the light was quite critical and a little tricky; it needed to be positioned behind the mirror so as not to blind the user but also illuminate the inside of the barrel directly above the mirror. I painted the recess where the LED is located with Tipex correction fluid to act as a reflector. You will see my solution to the problem in the diagram.

Schematic diagram








The next problem was some sort of power supply for the LED. These commonly need a supply of around 3 volts and also a current limiting resistor. I soldered a long lead to the LED, this lead was from a cheap earphone, each earphone lead actually has two conductors within the same sheath.   I then pass the lead down the barrel from the muzzle end and out at the breech and attached a battery holder containing two 1.5v batteries and also the required resistor to the lead.

Complete bore-scope










With the rifle held in the position vertical and the butt resting on the ground I was able to insert the borescope fully into the barrel, with a quick twiddle of the eyepiece I was able to bring the inside of the barrel into sharp focus. As I slowly withdrew the borescope the power supply lead was pulled up behind it.

The original viewer is only 12 inches long and even with the extension tube there is only around 15 inches of usable length so for a full inspection of anything but the shortest barrels the job needs to be attacked from both ends.

Now with the scope working well I thought I would try and capture the view on camera. A quick trip down to the local computer shop produced a bottom of the range webcam for £8 that works by plugging directly into the PCís USB port. After spending some time fiddling about I was still unable to get a satisfactory image using the camera lens so I pulled the camera apart and dispensed with the camera lens completely. After another lengthy fiddling session I found that I could get a good image by focusing the scope eyepiece directly onto the CCD screen of the camera.

Camera circuit board

I made up a spacer ring, cut from the barrel of a felt tip pen, about 1cm long. I attached this to the eye-piece with hot-glue and then hot-glued the camera circuit board to the spacer.

Now I know this contraption canít begin to compare with a shop bought borescope but for a total outlay of around £40 itís less than a tenth of the price and I quite pleased with the results.




If anyone would like to have a go at making this bore-scope and are having trouble locating the bore viewer please contact me at





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