|August - September 2002
Volume 37, Number
A Kimber Custom Shop .45 ACP and Smith & Wesson Model 625 .45 ACP were used in Brian Pearce's report on page 62. Coyote photo by John R. Ford. Kimber photo by Gerald Hudson.
For years Ive shot ground
squirrels with centerfire rifles loaded right to the maximum in velocity. Lately, though,
Ive wondered whether all that zip is wasted, because most of my shots range from 60
to 150 yards. A proper cast bullet load in .22-, .24- and .25- caliber cartridges is just
right for shots at those ranges and saves a few pennies and wear and tear on rifles.
Precision is the primary
consideration in developing varmint loads with cast bullets. A ground squirrel (gopher) is
about the size of a pop can, so a rifle that groups much over one inch at 100 yards is
just wasting lead. Fine accuracy depends on a bullet that fits the rifles bore, a
lead alloy for the intended velocity and correct powder.
Casting .22-caliber bullets may not
be worth the toil. Gas-checked .22 bullets you cast yourself cost about $2 per 100.
However, various reloading supply catalogs sell plain-jane jacketed .22-caliber bullets
for $5 per 100. So the $3 you save casting your own comes at the expense of your time
spent making the bullets. But reloading is a hobby, and satisfaction comes from the busy
Time spent casting .24- and
.25-caliber bullets is well worth the effort. Every time a bullet drops from one of these
moulds, I save nearly a dime over a store-bought jacketed bullet. (However, viewed from a
fiscally responsible position, Ive never saved a dime reloading or casting bullets.
The money has just been redirected toward new moulds, powders and bullets.)
For gopher (and target) shooting out
to 100 yards, .22-, .24- and .25-caliber bullets are fine with a muzzle velocity of 1,600
fps. At 60 to 65 yards, these bullets hit 1.3 to 1.5 inches high when sighted in at 100
yards. Once they reach 130 yards, though, they have dropped 3 inches and really plunge
after that. Higher velocities of 2,000 to 2,300 fps flatten the midrange rise to less than
.5 inch and drop at 150 yards to about 3 inches.
What bullet speed is chosen, though,
depends on the lead alloy of the
bullets. Bullets cast of wheelweights are sufficiently hard for speeds up to 2,000 fps.
Above that speed, accuracy begins to suffer because the higher pressure and velocity
distorts the bullet. Wheelweight bullets can be heat treated to harden them to withstand
velocities up to 2,400 fps or so.
I took an easier approach and cast
all the bullets listed in the load tables out of harder Linotype. To make sure Linotype
was hard enough to withstand these higher velocities, I fired 60 bullets with a muzzle
velocity of 2,100 fps from the Kimber Varmint .22-250 Remington. A three-shot group fired
after all those rounds measured just over one inch at 100 yards. A Hawkeye borescope
revealed only a bit of lead had accumulated in the leade and one short streak on the
leading edge of one rifling land. The rest of the bore was clean except for powder fouling
and a hint of blue the length of the bore from the Thompson blue lube. Most of the 60
bullets were RCBS-55-SPs that had only one lubricating groove. A patch soaked with Bore
Tech Bore Solvent followed by 10 brush strokes then three patches cleaned the bore.
Most cast bullets are designed with
a short body to fit between a bores opposing grooves and a forward section to ride
between the lands. This front portion aligns the bullet in the bore and guides it down the
bore. Any slop between the two causes misalignment. Wear of the lands in the first inches
of the bore makes for even worse shooting because the bullet is unsupported from the
start, like a butt in boxers, and wiggles down the bore.
The Lyman 225646 Super Silhouette 55-grain
bullet is one such bullet with a short body and long forward section that is supposed to
ride on the lands. This bullet also features an additional lubricating groove around a
nose that tapers from throat diameter to land diameter to align the bullet with the bore.
A bullet with all these features should be the answer to accuracy.
It didnt exactly work out that
way, however. The lubricating groove around the nose can only be filled with lube by hand.
If done with a sizer/lubricator press, the taper on the nose is completely filled. In
addition, the taper takes up most of the bullets nose so only a small portion of the
nose rides on the lands. In fact, only 43 percent of the length of the Lyman bullet
contacts the bore of a new .22-caliber barrel. Without that support accuracy suffered and
the Lyman bullet produced ho-hum results from the .223 and .22-250 Remingtons.
The RCBS-55-SP bullet also has a
nose that is supposed to ride on the lands. It provided a bit more contact with the bore
over its length than the Lyman bullet, and the result was several groups under one inch in
the .223 and .22-250 Remingtons.
The NEI 45- and 55-grain bullets are
designed with a long body of groove diameter. Sixty percent of their length is full
diameter body to match groove diameter. The nose of these bullets quickly tapers to a
point and doesnt ride on the lands. This NEI design shot well in the .223 and
The RCBS-243-095-SP bullet is a true
bore-riding bullet and shot very well in the 6mm Remington. In fact, half the loads fired
grouped under one inch at 100 yards. A good part of that accuracy was the near perfect
dimensions of the bullet as it dropped from the mould. The diameter of the forward section
measured .240 inch. When the nose of a bullet was pressed into the bore, the lands left a
light engraving on the sides. The bullets body diameter measured .2448 inch as it
dropped from the mould and .2445 inch after it was run through a .244-inch sizing die.
That diameter provided a slip fit in the chamber throat. My 6mm rifle is only slightly
worn at the front of the throat and 72 percent of the bullets length was supported
by the bore.
Unfortunately, a steady diet of 75-
and 85-grain jacketed bullets at 3,500 fps has pretty well cooked the first 4 inches of
the rifling of my Ruger .25-06 Remington, and the rifles precision the last few
years has gone downhill. The rifle used to group the RCBS-120-SP bullet with Unique,
H-4895 and H-4198 into less than 1.5 inches at 100 yards. But alas, of the 15 combinations
of powders and bullets listed in the tables, only five grouped tighter than 1.50 inches.
However, the rifle still groups Nosler 120-grain Partitions well under one inch with a
full load of H-4831.
E.H. Harrison, the technical advisor
decades ago to the American Rifleman, wrote in a January 1983 article Bullet Fit Is
the Key to Accuracy that jacketed bullets are guided by a bores grooves, and
they shoot well as long as the bottoms of a bores grooves remain uneroded. Harrison
cited military tests that found groove diameter increased only .0004 inch after firing
20,000 rounds of 7.62 Russian. Group size, however, only doubled from what it had been
after firing 14,000 rounds.
So for a bore with worn lands, like my poor
.25-06 Remington, a cast bullet with a relatively long body of about two calibers long
(like a jacketed bullet) would be best. All three of the .25-caliber bullets listed in the
load table had bodies one-half to two-thirds their length. Each one shot a couple groups
that were precise enough to hit a gopher at 150 yards. But compared to the 6mm Remington
loads, the .25-06's worn bore shot rather poorly. Perhaps the time has come to quit
procrastinating and have a new .25-06 Remington barrel installed.
All the bullets listed in the tables
were seated so the noses sat snugly against the rifling. That worked well for all the
bullets except two. The base of the long body of the NEI 55-grain bullet protruded .147
inch below the case neck. That exposure to powder gas can ruin a bullet’s base and
driving bands, but in this case the gas check covers nearly all the exposed base. In the
6mm Remington, the 2.89 inch loaded cartridge length was too long to fit in the Model 600’s
magazine. Cartridges measuring 2.80 inches in length fit in the magazine, but I wondered
if they would shoot as well. Not to worry, though, because the shorter cartridges grouped
a bit tighter. Could it be the 6mm’s relatively long neck, tight fit of the bullet in
the throat and the lands kept the bullets in
alignment with the bore?
Relatively fast burning pistol-type
powders usually produce good accuracy up to 1,600 fps in .22-, .24- and .25-caliber
cartridges. I say usually because Unique produced dismal accuracy in the .25-06 Remington.
However, pressures rapidly increase with these powders when velocities are stepped up to
2,000 fps and more. That increased pressure is too much for cast bullets to withstand and
accuracy suffers. One exception was Unique in the .223 Remington. This bulky powder filled
three-fourths of a .223 case, generated speeds of 2,000 fps and shot great. Seven grains
of Unique with the RCBS-55-SP bullet had a velocity spread of zero and grouped the bullets
into .59 inch.
At these higher speeds,
slower-burning powders like Varget, TAC, Reloder 7, H-4198, XMR-4064 and W-748 burn at
nearly half the pressure of pistol powders. Their pressures also rise over a longer period
to reduce the slam to a bullet.
The .223 Remington doesn’t burn
much of any of these powders with cast bullets. Some amounts were similar to those loaded
in the .357 S&W Magnum. So I tried a Small Pistol primer with several powders to find
if the primers provided enough flame to ignite these powders and at the same time reduce
pressure and turbulence to produce more even speeds. That was the case, at least somewhat,
with Unique. Winchester Small Pistol primers had a velocity spread of 55 fps compared to
68 fps for Winchester Small Rifle primers. But as Table I shows, Small Rifle primers
produced less velocity spread with other powders and 55-grain bullets in the .223.
If only the cost of running my
pickup were as inexpensive as these cast bullet loads I could drive out everyday to shoot
gophers. The .223 Remington with a 55-grain bullet and 7 grains of Unique cost 4.5¢ ready
to fire; the 6mm and 19 grains of Reloder 7, 7.5¢ apiece; and the .25-06 Remington with
26 grains of Varget and a 120-grain bullet, 8.75¢ apiece. Try matching those prices with
any cartridge loaded with a jacketed bullet or even a .22 Winchester Rimfire Magnum.
The gophers had just come out of
hibernation the middle of April. Shiny yellow buttercups dotted the wet ground below
snowbanks clinging to the shaded slopes. A dozen cow elk trotted out from a ravine, their
winter coats shaggy and bleached. I waited until the elk had wandered over the far ridge
before I started shooting.
I started with the .223 Remington
and the 55-grain RCBS bullet at 2,000 fps zeroed at 100 yards. From the solid rest of a
Harris bipod and with the Swarovski scope turned up to 12x, the gophers were easy targets
out to 125 yards. Much past that range, though, I had to hold over some to hit. After 100
rounds the bullets began to stick in the rifling when I pulled a loaded round out of the
chamber. That was from a dirty bore from lube and powder fouling. For extended shooting, a
bullet set back from the rifling would give trouble-free operation. The explosive effect
of the bullets on the little gophers carried pretty well out to 150 yards.
The 95-grain 6mm and 120-grain
.25-06 bullets didn’t show much eruptive action even up close. These bullets started
nearly 300 fps slower than the .22 bullets, yet only 100 fps separated them at 100 yards.
Perhaps the long length of the .24 and .25 caliber kept them from tumbling. Even though
the two bullets only drilled a hole through the gophers, the little varmints usually gave
up the ghost right where they stood, and hawks and ravens started to circle overhead.
I shot gophers until late afternoon. The 300
rounds fired cost less than half a tank of gas for my pickup.
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