A few weeks ago the phone rang. “You
gotta see this to believe it.” The rifle, a new Winchester, was in itsy-bitsy pieces,
blown to smithereens. The obvious answer to the problem was that some insane reloader had
filled the case with Bullseye, added some pure nitroglycerine, a few sticks of dynamite,
and then primed it with a small nuclear device. The reality was the wreck was accomplished
with factory ammunition and a very small mistake - a mistake of only seven thousandths of
an inch, .007 inch!
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This is what happened. The gentleman
who called me helped the young fellow bed the rifle on the sandbags and then walked back
to his own bench. A few seconds later he heard what he described as a rather loud
explosion, followed by the sounds of a car wreck - those sounds of rending metal and the
clatter of falling pieces. We should jump right in with the good news. Sitting in the
middle of this pile of devastation is a pretty stunned young man with one tiny speck of
blood on the end of his nose. He was, by some grand good fortune, uninjured.
The mistake and the chain of events
that followed are interesting. A year earlier the shooter and his father had borrowed a
rifle, a 7mm Remington Magnum. A spare shell from the previous hunting season found its
way into the box of .270 Weatherby ammunition. The mistake was not one of great
negligence, stupidity, fool hardiness or any other great fault. It was a very small
mistake with very big consequences; he fired a 7mm Remington Magnum cartridge in a rifle
chambered for .270 Weatherby. It was, if you will, a mistake any one of us could make. And
as you will see in a moment, there are several other combinations with a similar disaster
factor.
Looking at the destruction, we can
sort of piece together what happened - and even when I see it, I almost do not believe it.
The 7mm shell fits very tightly in the somewhat loose .270 Weatherby chamber neck and
headspaces on the belt. Even though the bullet is only slightly oversize, it creates a
zero-tolerance fit in the neck area, a situation that grips the bullet tightly in the case
instead of releasing it as intended. It is a little like mashing the gas pedal on your car
while standing on the brake, lots of horsepower is stored ready to spring.
The chamber pressure rises rapidly,
very rapidly. As we move through this incident, the bullet moves out of the case neck but
then rivets up just in front of the shorter case neck, making a bullet much larger in
diameter than the original .284.
Somewhere in these milliseconds, gas
begins to leak, probably from a blown primer. The gas blows the receiver ring apart.
(These Winchester actions usually break right along the raceway cut for the extractor,
because there is a sharp corner there.) When the receiver begins to open up like a clam,
it releases the barrel and the barrel moves rapidly forward.
Now, the rear of the case is totally
unsupported. The case head vaporizes, dumping all the high pressure gas into the action.
Most metal surfaces are painted with brass vapor. This gas finishes off the receiver,
bending the rails and sending the pieces of the front receiver ring into orbit. (They were
never recovered.) The same gas cuts away the rear locking surfaces of the bolt and
splinters the stock from the rear tang to the middle of the forend.
As incidental casualties, the scope
mounts are torn away from the rifle, and the scope is ripped in two in the middle. One
might credit Leupold with a stellar performance - the lenses are still intact!
The barrel traveled several feet downrange and
holds the strangest truths of all. The case is still in the chamber but blown away from
the belt backward. The barrel threads are perfect, and there are no bulges in the bore or
chamber area. The case is stuck but just a little - stuck about as tightly as you might
expect from a just-a-little-over-maximum load.
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Now the spooky part: The bullet is
still in the barrel. Well, at least the bullet jacket is in the barrel with its base just
in front of the case mouth. There is a 1/8-inch hole through the bullet base and most of
the lead core has been blown out of the jacket. The bullet was not a hollow tube type,
where we might expect such a failure. Instead it was a strong Remington Core-Lokt. As
mentioned earlier the base essentially moved faster than the rest of the bullet and
actually riveted up to about .300 inch in the chamber neck. And remember all this is about
a mistake a little bigger than the thickness of a human hair!
This small infraction of cartridge
rules is not unique. As I began to ponder the possibilities that might send us skyward on
a pillar of flame, several came to mind. The first is a .280 Remington in a .270
Winchester, an identical situation to the one above. In fact a fellow just wrote me a
letter asking if there was any harm in using his large supply of .270 brass to make shells
for his new .280. Superficially we might think, hey, go ahead - then we realize every
cartridge is a simple time bomb!
Years ago a friend in Colorado more
or less blew himself up by grabbing the wrong cartridge. He was shooting two rifles, the
offended one was a Remington Model 700 (the “indestructible one”) chambered for
.264 Winchester Magnum. I believe he fired a .308 Winchester in it. At first this seems
impossible, but the .30-caliber bullet headspaced the round, plugged the hole and by bad
luck centered the primer in the chamber. When the big light came, the case was totally
unsupported and released all the gas into places where gas should not be. The results were
similar to the pictures - little pieces, lots of little high-speed hot pieces. This fellow
was not so lucky. Shooting glasses saved his sight, but he looked like he had been shot
with a shotgun and then been in a car wreck. A .270 Winchester might chamber in a
loose-necked .264 with similar results.
Other combinations might turn into
bombs. A .338 Winchester Magnum would surely unhinge one of the big Lazzeroni chambers or
perhaps a .300 Remington Ultra. A .30-06 might rip a .300 Winchester, if the 06 had a long
seating depth, while a .458 would be a nasty misfit in a .416 Rigby. I am sure there are
many others.
It only takes one or two physical things to
make a disaster: a bullet large enough to plug the hole and an undersize cartridge case,
or a bullet that causes a crimped-neck situation. Actually it’s pretty easy to really
screw up big time. We all have to be wise and vigilant to avoid mistakes. Wear shooting
glasses, double check your ammunition and think all the time. Can’t happen to you?
Hey, look at the pictures.
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