I found this article over the weekend and thought it would be interesting to get other hand loaders opinions on primer applications across the board. John Barsness wrote it about 12 years ago.
Primers and Pressures by John Barsness
Many handloaders think a
primer is a primer, or differentiate
only between
�standard� and �magnum� primers.
But primer choice can make a big
difference in load performance�
and a REALLY big difference in
safety.
This has been known among
shotgun handloaders for years, but
too many rifle handloaders rarely
consider the side-effects of
primers. Various experiments (including
some I�ve performed myself
) have shown that the choice of
rifle primer can change the pressure
of the same load over 12,000
pounds per square inch (psi). This
means a load that produces a very
safe 58,000 psi with one primer
can produce an unsafe 70,000 psi
with another�and often there�s no
way for the home handloader to
tell the difference.
According to handloading lore, a
basement loader should be able to
tell when pressures get too high by
such signs as hard bolt lift, or marks
from the ejector slot of the bolt face
on the head of the brass. But such
�pressure signs� (in actuality signs of
excessive pressure) were relied on
long before present-day piezo-electric
testing equipment became standard.
Older methods of pressure
gauging were relatively inaccurate,
older rifles weren�t as precisely made
as today�s, and some older brass not
as hard. Recent testing has shown
that pressure signs such as hard bolt
lift and, in particular, brass flow
into the ejector slot indicate pressures
ABOVE 70,000 psi. Modern
bolt-actioned rifles can withstand
pressures of 65,000 or less almost
indefinitely, but if subjected to
70,000+ psi loads continually they
will eventually fail�the reason even
the hottest American magnum
rounds have a maximum factory
pressure rating of 65,000 psi.
If you�re lucky, continued firing of
over-warm handloads will result
only in certain parts stretching,
rather than breaking. Headspace,
for instance, might grow because
the bolt lugs are stressed. If you�re
unlucky, the rifle�s action can come
apart all at once. This happened a
few years ago to a friend who was
fond of loading rounds beyond normal
velocities�and hence pressures.
He got lucky. The right side
of the action blew, sending the
heavy scope over his left shoulder
and into the side of a building over
30 feet away�instead of into his
face. HE OBSERVED NO �PRESSURE
SIGNS� BEFORE THE RIFLE CAME APART but had
been shooting hot loads in the same
varmint rifle for over a year.
What all this means is that we
should be very, very careful about
which primers we use. The safest
technique is to use the exact same
primer listed in the loading manual
for any load. Unfortunately, this
means stocking almost every primer
made, an expensive proposition.
Instead I generally start with either
CCI 200 (standard) or Federal 215
(magnum) primers in rifle loads.
Both of these primers are among
the mildest of their type so should
produce safe pressures. (No, Federal
215�s are not the hottest magnum
primers around. They were the original
�magnum� rifle primers, so
many handloaders still regard them
as the hottest. But recent tests indicate
both CCI and Winchester
make hotter magnum primers.)
Only if the loading manual lists
another primer do I try it if the
CCI 200 or Federal 215 doesn�t
produce the desired results. For instance,
many loads list either the
Winchester WLR or Federal 210 as
a standard primer. The Winchester
is definitely hotter than the CCI
200, so I use it only in loads where
it�s suggested.
I learned this lesson after some experiments
with pressure-testing. I�d
worked up a load in a .270
Winchester rifle that showed no traditional
pressure signs but had substituted
a Federal 215 when the
Federal 210 listed for the load hadn�t
produced the accuracy desired.
Then I had this load tested in a
piezo-electric lab. The average pressure
was almost 68,000 psi, well
over the limit for the .270.
Substituting either the Federal 210
or CCI 200 dropped pressures into
the low 60,000 range.
This is why most loading manuals
advise you to stick to the recipe.
Modern bullets can create far different
pressures than the fairly standardized
bullets of 40 years ago�but
switching primers can make even
more difference. Be careful!
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