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Posted: 6/12/2015 3:31:18 AM EDT
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Buttoned rifled barrels have rifling that is swaged (pressed) with a button and are done in one pass. Broached barrels have rifling cut with a broach and mostly done on short barrels such as handguns. Broaches have multiple cutting steps on them and are also a one-pass process. I see advertising on FN's website calling the barrels "buttoned broached". Do they make buttons now that actually cut instead of swaging?
Edit to add- I think SA M1Garand barrels were broached? Seems like I read this somewhere and saw a film of the barrels being rifled after they were contoured. |
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That is confusing.
The normal distinctions: Button rifling is having all the grooves pressed in the bore in one pass by a carbide "button" Broached rifling is having all the grooves cut in one pass with a "rifling broach" Cut rifling is having each groove cut in several passes by a cutting head. Rotary forging, hammer forging, cold hammer forging, or flow forming are all the same process of beating a steel billet over a mandrel that has a reverse image of the finished rifling on it (and sometimes the chamber as well) to make the bore and the rifling at the same time. I am pretty sure that button-rifling was invented to increase barrel production (and reduce time and cost) during World War 2. Springfield did outsource barrel manufacturing, any of the first three rifling methods could have been used in their barrels. The US military got their first hammer forging machine in 1974-75. That was the first one in the US. |
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