Quote:
Originally Posted by Bob Phillips
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Some of the cylinders were reconditioned by the Van der Horst Corporation. These cylinders were reconditioned by honing the used bores out oversize, and then chroming the bores back to standard size. This technology had been developed through a patented process by a Dutch engineer named Dr Hendrik Van der Horst in 1936. He called his patented process "porous chrome". He improved his chrome plating process again in 1943 and set up a plating company in the USA called Van der Horst Corporation of America ( later United Van der Horst). His challenge had been to create a plating process that was not as hard and smooth as traditional chrome plating. The chrome needed to have the ability to retain oil in it's surface. This was accomplished by chroming the bores in the traditional way but then near the end of the process to reverse the polarity of the electrical charge which attracted the chromium solution onto the bore surface and in so doing, create a series of tiny grooves and furrows which would retain the lubricating oil. The finished bore has a frosted appearance but is still very hard. ...
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Funny you mentioned bore diameters and hard chrome plating. My father was an Olympic shooter and had won a Queen's Medal for Champion Shot as a young soldier. He was a big deal for all things shooting. When the FN C1A1 rifles first appeared, he naturally tested as many as he could find in order to get a very competitive rifle as he went after more Queen's Medals. I remember him telling me that the best rifles were the absolutely earliest serial numbers and first batch of barrels. It seems they had been bored with new sharp tooling and were pretty good as barrels went. Then someone realized they needed to be chrome plated, so these barrels had chrome on top of specified dimensions. They were tight! And shot like crazy! He ended up with 5 Queen's Medals, 1 with a No.4 and 4 with FNs.