Broken Crosshairs

The flat crosshairs are original and the fine crosshair is modern polycarbonate.  The original flat post is missing as a result of breakage. It proved impossible to stabilise the remaining posts and the ony solution was a new set of fine crosshairs

Broken Crosshairs on Vintage Scopes

The old optical engineers knew a thing or two about lenses, glass, crosshairs and making optics durable.  Originally crosshairs were constructed out of hair or spiderweb, these materials being sufficiently thin and strong.  Interestingly a spiderweb crosshair was unaffected by recoil; being so light, thin and strong it was undamaged by acceleration or deceleration while the scope that housed it was often stressed.  Legend has it the old German optical engineers kept specially bred spiders in jars in their workshops to provide silk crosshairs for the instruments they built. Many years ago I experimented with spider web for repairing damaged reticles but found the web of the common spider to be too fine.  I next tried fine human hair but found it to be translucent as was fishing line.  Many modern scopes use wire crosshairs, which can be flattened to various degrees to change the width. These wires are usually silver in colour, but appear black when backlit by the image passing through the scope's optics.  Wire reticles are simple, as they require lines that pass all the way across the reticle, and flattening the wire make duplex crosshairs possible.  The advantage of wire crosshairs is that they are fairly tough and durable, and provide no obstruction to light passing through the scope.  I experimented with various types of fine electrical wire but found it was too thick for modern high-magnification scopes and often had a “crinkly” appearance as it was impossible to iron out the twists.  Etched reticles are more modern and the first suggestion for etched glass reticles was made by Philippe de La Hire in 1700.  His method was based on engraving the lines on a glass plate with a diamond point.  This technology proved to beyond the scope of my home workshop.  At this point I called in my oldest friend who is a physicist-engineer and his researches revealed that fibres of modern synthetic material such as found in Paracord and Cordura are just right.  They make simple uniform crosshairs of correct thickness and are neither translucent nor distorted by weaving.

The biggest problem was what we will call "Crinkly Crosshair" or "Crosshair Slump".  The solution came with experimentation and perseverence until tautness was achieved.  A fiddly business.

The occasion for all this experimentation was an incident of monumental clumsiness on my part.  While disassembling a Pecar rifle scope in order to change the crosshair reticles, I broke the delicate steel filaments thus rendering my favourite hunting scope useless.  The fix became a fascinating project that has continued on and off for twenty years.  The Pecar range of rifle scopes are now discontinued but there is still a lively trade in used models and spare parts.  Unfortunately Pecars and other older European scopes now have a collector value and they are gradually getting pushed beyond the reach of the ordinary shooter.  €600 can still buy a fine example of the optical engineer’s art although most serious shooters choose to spend much more on modern scopes with etched glass crosshairs which must be returned to the manufacturer for maintenance and repairs.  On a recent trip to visit al Conroy, an old friend, now retired from the gun trade, I was given an original boxed Pecar crosshair reticle of the German Post type.  It was two full years before I got around to examining it and when I did so I found it too was damaged – probably in exactly similar circumstances as my own.  The post was partly detached but a repair was possible.  I shoot more targets than game these days and I had an idea I wanted to try.  Years ago, back in the sixties, Weaver produced a double reticle which functioned as a rangefinder.  By placing the double horizontal lines over a target, its range could be reliably calculated.  Would the same idea work for the long range shooter?  In situations where the target is beyond the adjustment range of the scope would double crosshairs serve as long and short range sights?  The idea is not new – mil dot reticles are common.  The difference here is that the range of adjustment of the scope is 24 moa and 60 moa is needed at long range for cast bullets which necessarily travel at lower velocity and drop more.  I decided to give it a try and reluctantly removed the damaged crosshairs with a pair of pliers.  The force required to extract then was testimony to the skill of those old engineers.  I would be working with synthetics.

Range finding crosshairs.  It's an old idea and a good one.  The plan was to zero the centre crosshair at 50 yards  and take pot luck with the lower crosshair which fortuitously and through inspired guesswork landed at almost 300 meters

The almost finished product.  The lower crosshair slumped overnight and had to be re-done but the concept worked. A 50 and 350yard zero.

 Having extracted a tangle of fibres from an old Cordura strap I isolated one filament and anchored both ends with sticky paper.  I stretched it across the housing and glued it into place with my wife’s nail varnish.  This was a failure as the relatively slow-drying varnish lacked the strength to tension the filament and I ended up with saggy crosshairs.  The project stalled pending the arrival from Ebay of a little bottle of fast-bonding glue used to attach false fingernails.  Fashion has its uses.  The second attempt was blessed with success and all three crosshairs looked tight.  I still hadn’t the faintest clue what the interval between the two crosshairs would be at 10x magnification so I set up the scope at 50 yards and used a sheet of paper and ruler.  The interval was 22.5 inches exactly or 45 inches at 100 yards. A minute of angle is 1.047 inches at 100 yards so I had a 43 moa long range crosshair.  I consulted my bullet drop table which showed that for a 50 yard zero a 45 calibre bullet at 1300 feet per second dropped 43 moa or about 160 inches at 360 yards.  I was zeroed at 50 and 360 yards which is close to 300 meters – not bad for an old codger doing a bit of inspired guesswork!  I went to bed delighted with my handiwork and when I went to admire my new reticle the next morning, the 43 moa crosshair had sagged!  Well, at least the idea worked in principle and a half hour with the glue and the magnifying glass would finish the job.

The raw material.  Polycarbonate fibres from webbing