Stealth Pilot wrote:
On Fri, 21 Dec 2007 05:10:57 GMT, Trevor Jones
wrote:


DoN. Nichols wrote:



a general question on the same topic...

how did the old craftsmen drill their barrels?
some of these barrels, say for a shotgun, are almost too thin to hold
with any real purchase. similar for tapered barrels.

did they drill the hole through the blank, plane out the rifleing,
then turn down the outer diameter?

Stealth Pilot

Shotgun barrels started out with straight sides, and then get the
contour put on after the bore is finished. The walls are quite thick
enough, if you look at the chamber end.
First the hole through, then the reamers up to just below size, then
the lapping/polishing out to final dimensions. Some chokes were done
using tapered reamers, some by swaging down the outside of the blank
after polishing, some are machined in the bore after manufacture.

It is said that Harry Pope, one of the legends of rifle barrel making,
used a twist drill on an extension to drill his barrels. His barrels are
still sought after.
Proof that great work can be done with less than optimal tools!

If you get a chance, find a copy of the video "Gunsmiths of Colonial
Williamsburg". It follows through the whole process of building a
Flintlock rifle, using a forge welded barrel blank. The interesting
thing is to see the drills and reamers used to open and clean up the
bore there. Really low tech, but effective stuff.

Another video that covers a lot of the detail, is the Lautard video of
Bill Webb's Rifling Machine. It covers a little more modern approach of
drilling, with a pressure coolant fed gundrill, and a cut rifling head.

Most barrels these days are button rifled. It is a fast, accurate
enough process that leaves a decent barrel in one pass of the rifling
cutter, and does not require near the investment that a hammer forging
machine requires. The rifling is done by a carbide button being driven
or pulled through the barrel by hydraulics, usually.

Modern rifle barrels start out as a large diameter round bar. The hole
is drilled, the rifling installed, and the outer contour cut. At least
for barrels other than hammer forged, which are a whole different
process, that will never be suitable for anything but volume production.

Cheers
Trevor Jones