From: "Peter Sarony", [EMAIL PROTECTED]
Sorry to disillusion you, but ECM rifling is neither that simple, nor is it
that wonderful. The electronics are complex and it takes considerable
development for each twist rate and pattern of rifling to be developed. It
is therefore costly unless very long runs of a particular specification is
involved. One of the other considerable disadvantages of this method is that
the gap between the electrode and the bore wall is jumped by the eroding
spark. This erosion milling thus cannot take a sharp corner form but is
radiused from the sharp pointed corner of the electrode. In my opinion, the
best form of rifling is still the full form mandrel hammer forging method,
which enables a desired micro taper to be accomodated on the finished
rifling, work hardens the barrel material, is rapid and wholly repeatable.
It does require, as do all such processes, a high level of operator skills
in developing the the tooling and feed rates, mandrel maintenance and so
forth, but the finished barrels are potentially unsurpassed in quality and
longevity.
Regards,
Peter Sarony, Armalon Limited.
--
Which is why they use it on AKs - lots of identical barrels.
Steve.
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