OK: I am sure if I get this wrong someone will jump on me. Please feel free to correct me.
Halo
To encircle with or as if with a halo.
Halos are most often associated with the stamping of harden metal such as barrels, extractors, breach blocks and some pins.
As the stamp makes its indent the metal under the stamp must go somewhere, in more ductile metal it is absorbed over a large area but in harden metals this absorption is resisted and some of the metal is pushed up causing a slight rise or bump. After bluing this bump wares at an accelerated rate, as a result the bluing in this area takes on a lighter appearance resulting in a â??haloâ?. A change in crystalline structure (hardening) may also occur adjacent to the stamping reducing the effectiveness of bluing agents and over time cause the same halo effect.
If a gun is refinished this slight bump/hardening is removed and a halo will not reform naturally.
You can simulate the difference between hard and soft metals by using a candle and pencil tip and varying the temperature of the candle.
Vern
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