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100-Yard
Accuracy Results of Selected .38 and .357 Magnum
Cast Loads in
a BSA Single-Shot and Marlin Cowboy Rifle
The proof of
the pudding in any long gun is it will do at 100 yards. Not all handgun loads provide linear dispersion
in proportion to the range, when fired from rifles, you need to test. Wad cutters do well at 50 yards, but not at
100.
I tested
ordinary .38 and .357 handgun ammunition for which I had previous data. These included match-grade Norma 158-gr. lead
round nose factory ammo, hand loads with Speer swaged lead round nose and
semi-wad cutters and hand loads with cast lead, flat nosed cowboy slugs. All were standard velocity loads fired from
my BSA Martini with 6X Unertl small game scope for five consecutive 5-shot
groups at 100 yards. The best loads in
the Martini were tested again in a Marlin 1894 with 2.5X Weaver scope.
Results are
summarized in the accompanying table.
Click
on this link for the Excel Spreadsheet
Norma
158-gr. LRN factory loads averaged just less than 3” at 100 yards from the
BSA. Hand loads with swaged lead round
nose and semi-wad cutter ammo in .38 Special cases didn’t shoot quite as well,
but did stay under 4 minutes of angle, having useful field utility.
The most
accurate 100 yard cast loads used the Hunter’s Supply cast 190 LFN of 92-6-2
alloy, sized .358 from Midway, with 4.3 grains of Bullseye in .357 cases. They
averaged 2.18” in the BSA and 2.36” in the Marlin. This is the same bullet as NEI #191A. I cast some of those also from wheel weights
tested them, getting comparable results as long as velocities with softer wheel
weight alloy were subsonic. I normally use 3.5 grains of Bullseye in .38 cases
and from 4.0 (if low noise is important) up to a maximum of 4.3 grains in .357
cases based upon accuracy results.
Supersonic loads do not group as well at 100 yards as the slower ones,
due to transonic buffeting as projectile velocity decays below the speed of
sound.
My advice is
not to magnum-ize it, but keep it handgun-caliber lead loads for rifles slow,
accurate and quiet. A good working
velocity range is from 950 to 1050 f.p.s. In a 24” barrel this gives a peak
decibel noise level of less than 90dB, so there is no crack to disturb the
neighbors. A big flat-nosed bullet is
effective on groundhogs, wild turkey and larger edible critters raiding your
garden. Bon appettit!
Sidebar to accompany .38
Special Test results
I was very pleased that my own
wheel weight metal, cast Saeco #348 wad cutters, loaded as-cast, unsized, lubed
either with Lee Liquid Alox (LLQ)
or Rooster Jacket tumble-on lube (RJTL), in unsized fired cases, decapped and
flared only, with my standard charge of 3.5 grains of Bullseye,
crimped in the revolver crimp groove and profiled in the Lee Factory Crimp Die
shot equal to factory loaded Winchester wad cutter ammunition. The results also indicate that using the same
simplified loading, method with soft-swaged Remington factory wad cutter
bullets, enables you to assemble your own accurate match ammunition to equal or
exceeding the grouping of factory wad cutters now available.
Commercial hard cast bullets of
92-6-2 alloy, sized, to .357” or 358” diameters did not shoot as well as my own
unsized wheel weight cast bullets lubed with LLQ or RJTL. The Remington soft swaged HBWC
bullets shot wonderfully when flush seated, using the black dry lube which came
on them. None of the cast double-enders
grouped as well when flush seated as they did when seated out and crimped in
the crimping groove.
I believe that this is attributable
to two causes. First, flush seating
results in increased free bullet travel of the wad cutter bullet during initial
acceleration, when fired in the .357 chamber.
Also, when the top driving band is seated below the
case mouth, crimping and profiling in the Lee Factory Crimp Die results in a
slight reduction in its diameter.
When bullets are seated out and crimped in the crimp groove with the top
band exposed, its diameter remains as cast, or as-sized.
I believe that either an enlarged
front band, or an expanding hollow base, as in the Remington HBWC bullet, aid in providing a positive gas seal, which
reduces leading and bullet deformation, which hurt accuracy. There was no leading whatever with the
factory HCWB bullets or the unsized
cast bullets lubricated with either LLQ or RJTL.
I did some limited firings of
my .38 Special Colt Officer’s model from sandbags to check each load. The loads which shot well in the Martini also
shot well in the Colt. All of the cast
wad cutters were tested with the same 3.5 grain charge of Alliant Bullseye, because this is proven reliable in past
experience. The results would indicate
this is the case.
The soft-swaged Remington
hollow-based wad cutters shot consistently well, even with somewhat lighter and
heavier charges than those usually recommended.
I found that a somewhat heavier charge of Alliant Bullseye,
than the often recommended 2.7-2.8 grains was needed with the HBWC bullets to approximate the velocity of factory wad
cutter loads and that whether firing in the Martini Cadet rifle or the 6” Colt
revolver that a charge in the range of 3.0 to 3.2 grains was correct.
When Spring weather permits, I hope to do some confirmation firings outdoors at 50 yards and also shoot some lead round nose and SWC bullets from the rifle at 100 yards to see how well a .38 Special rifle fares as a mild and quiet small game rifle. So stay tuned!
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