What are the differences between cold-hammered, button-rifled and cut-rifled barrels?
The raw material for a hammered barrel is a relatively thick steel blank, which is worked by drilling, grinding and polishing. It is then placed over a mandrel and shaped by hammering. The shape of the mandrel corresponds to a reverse image of the barrel including grooves and lands. Hammered blanks are often polished afterwards. Finally, the chamber for certain calibres is also worked by hammering. It only takes a few minutes to produce a barrel in this way but the machinery is very expensive, which is why only larger manufacturers use this method.
Button-rifled barrels are also made by drilling, grinding and polishing. The rifling pattern is then pressed into the barrel with a tool called a button. Afterwards the barrel is polished with a lead rod and grinding paste. This method is frequently used by smaller manufacturers, as it does not require such expensive tooling.
The oldest method of rifling barrels is by cutting. The first steps are the same as for the other two methods described above. A tool fitted on the end of a rod then moves through the barrel, forming the grooves by gradually cutting deeper and deeper on each pass. This method is very time consuming.
Good barrels can be made with all these methods. Button or cut-rifled barrels are generally the best.