I
had always assumed that as long as my selected primers caused things to go
boom with 100% consistency, my primer selection interests were satisfied.
My first insight that primers from different manufacturers may perform differently
was during one summer of testing .44 mag loads. I found a change of primer
could change the impact point by 1½ inch at 25 yards, and affect the accuracy
and velocity. Ive also found that the best primer for one cartridge and/or
load may not be the best for another set of components -- thus my habit of
including primer comparisons in any new load development.
For
a current development session, I selected the following five small rifle primers
for testing with a 6 1/2" barreled .454 Raging Bull:
Winchester (WSR)
Remington No. 7 1/2 Bench Rest
CCI 450 Magnum
CCI BR-4 Bench Rest
Federal Gold Medal Match GM205M
The testing was performed with the cartridges at two different environmental
temperatures (ambient) and at a reduced temperature. I will be the first to
identify the reduced temperature testing in the manner I performed it was
not the optimum testing environment. An example of the obvious is once the
cartridges left the icebox, they were exposed to ambient temperature and a
warmer revolver, thus some impact would be expected. As noted below, that
exposure was minimized as much as possible. The reduced temperature testing
was developed as follows:
Cartridges (qty 5) were stored in individual plastic containers and placed
in a freezer for 2 hours at 0 degrees temperature. The containers were then
placed in an insulated icebox and covered with ice for transportation to the
range. The time from removal from freezer to final shot fired was approximately
47 minutes. The individual containers allowed me to leave the cartridges in
the icebox until time to shoot that particular primer group. Tests indicated
the cartridges ranged from 18 to 20 degrees at the time the revolver was loaded.
All cartridges were fired within 11 minutes after starting and each 5 shot
primer group was fired within 90 seconds of being taken from the icebox. Since
the average velocity of the last two shots (all ten groups at reduced temp.)
was only 1.8 fps faster than the first two shots, I would assume the environmental
temperature did not noticeably affect the cartridges prior to shooting.
The testing was performed over a six-day period,
with five rounds loaded and shot for each primer each day. Ambient temperature
for tests day 1 and 2 was 72 and 74 degrees. Ambient temperature for day 3
and 4 was 64 and 62 degrees (cartridges were 18-20 degrees at time of test)
and the final ambient test temperature for day 5 and 6 was 88 degrees.
The primary interest for these tests was velocity performance, consistency
of velocity performance (ES) and accuracy. For the sake of brevity, I'll only
indicate that the cartridge components were Winchester brass (new) sorted
for 1.381" length, 24.1grs. of W296 powder, and hard cast, gas checked
360 gr. bullets. RCBS .454 dies were used and seating and crimping were
done separately. O.A.L (1.777") was compared between groups to
assure consistency. The Chrony was placed 9ft. from muzzle. Accuracy tests
were conducted from bench rest with iron sights and targets were placed at
25 yds.
Test results are as follows:
Velocity
Results (feet per second)
Summary
There
were no misfires and one could say they all performed adequately. But at the
risk of offending the reader and their favorite primer, I suggest that for
this combination of components, the CCI BR-4 did out perform the other primers.
To any reader I did offend, let it be know that my standards, the CCI 450
and Remington 7 ½, came in 4th and 5th place! Like many
tests, the results reflect my skills and this particular set of revolver and
loading components at this particular time but I would like to think it
offers a result worth following up on for long-term usage. And with that I
wish all good shooting - Dan.
