🚀 go-pugleaf

In article <cbkubd$h1$1@grapevine.wam.umd.edu>,
John Bischoff  <mingol@adelphia.net> wrote:
#When using the "Ken Waters" method for measuring case head expansion, how far
#from the base of the case does one set the micrometer?
#I see that some measure in the extractor groove.
#I think some measure at or near the middle of the web area.
#And surely some measure at the web/case wall interface.
#Or is there any kind of standard for this measurement anyway?

  My memory is that it is the wide place above the web/case wall
junction.  IIRC you can actually see it as an almost shiny ringed area.

  If  nobody else remembers - I might even go back to my notebooks and
Ken Waters' articles.
--
--henry schaffer
hes _AT_ ncsu _DOT_ edu


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Learn about rec.guns at              http://www.recguns.com
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Ken Waters uses the expansion ring, which is the area just ahead of the
web/case wall interface. On fired cases, this will be the slightly shiny
ring that will also appear to be bulged out, that is just ahead of the
actual web of the case. His reasoning is that using the expansion ring will
allow more accurate measurements without any possibility of interference
from the rim. He also follows the belief that he does get more accurate
measurements, and therefore a better indication of pressures with all loads.
This method does work very well in developing loads, especially for calibers
for which there is little, if any, information on reloading for. With his
method you will find maximum, safe loads for a particular cartridge/case
lot/firearm combination that will yield good case life and adequate
velocities. Ken's method works very well with all action styles of either
front or rear locking lugs.

On the other hand, Bob Hagel promotes taking the reading from directly over
the web of the case. For this you would measure behind the expansion ring.
You may also have to relieve the rim a little bit to make sure that it does
not interfere with your micrometer reading. When you measure in this
position, you are able to locate the absolute maximum load for your
particular cartridge/case lot/ firearm, so that you can back it off just a
bit and have a safe, maximum hunting load that may not give long case life
but will give you the highest velocity hunting load for your rifle, assuming
you are satisfied with the accuracy. Bob's method works best with front
locking lug, bolt action rifles for hunting.

If a measurement is taken from either the extractor groove or from the rim
(not recommended at all as there is to much variation in rim diameters from
case to case, even within the same lot of brass), then what you are actually
measuring is primer pocket expansion. And an increase in diameter of the
primer pocket is an indication that you have already exceeded safe
pressures.

Shoot straight (and safely)
Bob

"John Bischoff" <mingol@adelphia.net> wrote in message
news:cbkubd$h1$1@grapevine.wam.umd.edu...
# When using the "Ken Waters" method for measuring case head expansion, how
far
# from the base of the case does one set the micrometer?
# I see that some measure in the extractor groove.
# I think some measure at or near the middle of the web area.
# And surely some measure at the web/case wall interface.
# Or is there any kind of standard for this measurement anyway?
# Best regards
# John



-----------------------------------------------------------
Learn about rec.guns at              http://www.recguns.com
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