If you remember, I discussed the long range efficiency of Lapua’s
Scoremax 22 ammunition a couple of months back. Basically I said that because of
the combination of its subsonic velocity and greater ballistic coefficient (due
to the longer length of its 48 grain bullet) it was able to hit the 100 meter
rams at higher velocity and with more weight than a standard subsonic 22 bullet.
Well, that leads us to the next logical question "How does a standard 40 grain
subsonic bullet’s hitting power compare to a standard 40 grain supersonic
bullet’s hitting power at 100 yards?"
There’s a fair number of silhouette shooters that like to shoot the
supersonic stuff figuring that there’s going to be more impact on the rams at
100 yards. Intuitively, it makes sense. Often the differences in velocity
between a subsonic and supersonic 22 bullet can be substantial. However, we also
know that a supersonic bullet will have to deal with the turbulence of breaking
through the sound barrier, but that’s an accuracy issue. What about velocity?
Well, we also know that because of the increased air flow over the
supersonic bullet that drag will be increased as well. The question now becomes
"In spite of the much greater drag, will the substantially greater initial
velocity of a 40 grain supersonic bullet allow it to hit the ram at 100 yards
with more velocity than a subsonic 40 grain bullet?" To tell the truth, I wasn’t
really sure. Even though the subsonic bullet is subjected to less drag and will
lose less speed as a percentage of its muzzle velocity, is that enough to
overcome the supersonic bullet’s substantially higher speed? I decided to check
it out.
What I would do is compare the performance of high quality supersonic
40 grain ammunition (Eley Scorpion) against the numbers of the 40 grain subsonic
ammo that I used in the Scoremax evaluation (PMC Rifle Match).
| |
Muzzle Vel |
100 Yd Vel |
Vel Drop |
|
Scorpion |
1248 fps |
1012 fps |
236 fps |
|
Rifle Match |
1036 fps |
936 fps |
100 fps |
Both brands would be chronographed at the muzzle and at 100 yards with
my Oehler 35P chronograph. Here are the subsequent numbers:
The numbers are kind of interesting. We see that Eley Scorpion lost
far more speed i.e. just about 19% of its muzzle velocity at 100 yards. On the
other hand, the PMC Rifle Match lost less than 10% of its initial velocity. So,
we see that because the subsonic bullet doesn’t have to overcome as much drag,
it’s going to lose less velocity.
Never the less, horsepower does make a difference. Because it’s
starting off much, much faster, the Eley Scorpion will definitely put more hurt
on the 100 yard targets (76 fps more to be precise) in spite of the fact that
it’s going to be losing more velocity overall.
This little experiment shows that the supersonic route in silhouette
does have value, but also be aware that supersonic bullets are more sensitive to
the wind. Additionally, in general, most supersonic ammunition has not
demonstrated the degree of accuracy that subsonic ammunition delivers.
Remember I said "in general". There are always exceptions.
Consequently, if you want or need to use supersonic ammo because of sticky rams
at your club, use high quality products like Eley Scorpion. When the wind is
calm, this stuff will shoot an inch or better at 100 yards. (Note: Eley Scorpion
is no longer available but Eley High Velocity is a good substitute.)
The Idea
Quite often ideas will come to me when I’m laying in bed at night. You
know, it’s that period just after you’ve turned off the light, fluffed up your
pillow, and closed your eyes. Many people (the lucky ones) will instantly fall
fast asleep. Not me. I’ll just lay there and start thinking, and thinking, etc.
My thoughts will wander all over the place and then ideas will start coming out
of no where - ideas that often have no connection what so ever with what I was
thinking about just the second before. I’m sure there are those that would say I
was being delusional or perhaps that I was hallucinating. They could be right.
Anyway, I was in one of those states, when it suddenly occurred to me
that primers are absolutely huge in comparison to the size of the flash hole
that they’re sitting on. Think about it. A flash hole can’t be more than 20% of
the size of a primer. So that’s around 80% of the primer material that’s
probably not making down the hole into the powder. Why is that? Why doesn’t
someone just either make smaller primers or larger flash holes?
Upon some reflection, I thought that it probably makes sense to have
oversized primers to accommodate mechanical tolerances regarding firing pins,
chamber size, etc. After all, not all firing pins are located exactly in line
with every cartridge’s primer flash hole.
Nope, it seemed that having larger flash holes would make more sense.
It then occurred to me that if the flash holes were larger, more of the flaming
primer material would hit the powder and more complete ignition should result.
If ignition is more complete, it should result in better velocities and
accuracy. Gosh, what a great idea.
So, how could I go about testing this theory? Well, I’d load up ten
regular 357 mag cases and then fire them over my chronograph and check the
velocity, standard deviation of velocity, and accuracy. I’d also drill out the
flash holes of ten additional cases using a 1/8th inch drill. This resulted in a
huge flash hole in the case head with just a little narrow rim for the primer to
be seated against. I’d then fire the modified cases using the same load and
compare the results. Theoretically, the modified cases should deliver greater
velocities, lower SD’s, and greater accuracy.
My test gun would be a Contender equipped with a 14 inch SSK barrel. A
Leupold 2.5 X 8 nestled in a set of Weaver 4X4 scope rings provided the optics.
My test load would be a pretty standard silhouette combination
consisting of 16.5 grains of H110, Sierra’s excellent 180 grain silhouette
bullet, Starline brass, and CCI’s small pistol mag primer. The bullets were
seated with Redding’s competition die and the profile crimp was also provided by
a Redding die.
After reflecting a little more on the subject, I began to wonder if
the increase in primer flash would boost ignition too much, too fast, and result
in out of control pressures. In fact, I got worried enough about it that I
called a very good friend of mine who works for one of the primer manufacturers.
He kind of scratched his head for a while and then admitted he didn’t have a
clue what would happen. He just advised that I go slow. Well the ammo was
already made up and I wasn’t going to tear it all down in order to reduce the
load. I figured the Contender should be able to handle the situation.
Well I got everything set up at the range and fired off the ten
cartridges with the standard flash holes. The chronograph numbers were actually
pretty good and accuracy was around 2 inches at 100 yards. (I should explain
that this barrel is over 20 years old and is for all practical purposes shot
out. I plan to re-chamber it one day in 357 Max or maybe even 35 Remington and
use it for a pig gun.)
I have to admit I was a little nervous when I loaded the first case
with the oversized flash hole. I had no idea what to expect. I slowly squeezed
the trigger, the gun fired, and everything ---- was absolutely normal. No
blinding flash, no loud thunder clap, no punishing recoil, no pieces of shrapnel
flying. Everything just seemed ---- ok.
A glance at the chrono showed the velocity of that first shot to be
right in the same range as the average for the first group of ten shots. Well,
that must have been a fluke. I should be getting more velocity. I then fired off
the remaining nine cartridges. Here’s the results.
| |
Normal Hole |
Oversized Hole |
|
Velocity |
1620 fps |
1610 fps |
|
Std Dev |
7 fps |
10 fps |
|
Group |
2.2" |
2.1" |
Results? There was no practical difference between the performance of
the loads from a statistical or accuracy point of reference. Heck. I guess I’m
not a genius after all - what a surprise. Well, it was an interesting idea and
I’m glad I tried it out. As they say "Even negative information has value."
Brownells Screwdriver Kit #1
Any silhouette shooter that has ever owned a Thompson Contender with
more than one barrel knows about the necessity of having a screwdriver kit in
your shooting bag. For instance, in order to change barrels, we need a blade
type screwdriver to take off the forend. If we want to remove the grip, we now
need an Allen wrench or hex head driver.
If we should want to put on a scope or switch scopes, we first have to
remove the open rear sight which requires one size blade to take out the
elevation screw and another size blade for the smaller attachment screws
underneath. Then we have to put on the base and rings, again with two different
size blades or perhaps a hex head. Quite often the ring straps will use the new torx screws and require special screwdrivers.
The same situation applies to other guns used in silhouette shooting as
well. The point is that the serious silhouette shooter is constantly
making adjustments, changes, or even repairs on their guns, and quite
often those changes are occurring out at the range without the benefit of
the full breadth of tools that we have at home.
This kind of activity demands that we have the basic tools we need on
hand to do the job. Subsequently, the shooter oriented screwdriver kits that we
take to range must meet at least four criteria.
1. They should be very versatile and contain as many items as possible
so they can meet almost every expected and unexpected situation.
2. Kits should be the best quality available. I don’t know about you,
but when I’m working on a silhouette gun that cost me big bucks, I’m not going
to use some cheap, no name tool that was made in a Chinese sweat shop.
3. Kits should be compact in order to take up as little space as
possible in our shooting bag. Heavens only know I’ve already got everything but
the kitchen sink in there already without adding a bunch of screwdrivers, allen
wrenches, etc. Obviously, this criteria is in direct conflict with the first
criteria as the more items you place in the kit, the less compact it will be. Of
course you can go overboard in the opposite direction as well and have a very
compact kit with hardly anything in it. We also need to keep in mind that there
is one set of requirements for making adjustments/repairs at the range and then
there there is a very different set of requirements for doing the same out in
the field on a hunt. The field kit we carry in a backpack on a hunt obviously
should be extremely compact and light weight. Naturally it will contain fewer
items than a range kit. A range kit will usually be larger because we’ll only be
carrying it from the car to the shooting bench. My remarks here are geared
primarily at range use.
4. The individual pieces of the kit should be easily replaceable.
Losing something out of the kit is almost inevitable over a long enough period
of time and it shouldn’t take an act of Congress to get another one.
I’ve used a number of these shooters kits over the years and I have to
say that the Brownells #1 Magna-Tip is probably the Cadillac of the bunch as it
comes the closest to perfectly meeting the four criteria. Let’s compare it to
our requirements one at a time.
Versatility - The kit contains the following:
- 7 - inch and a half long hollow ground bits for slotted screws (for
extra reach)
- 4 - one inch hollow ground bits for slotted screws
- 4 - inch and a half hex bits
- 6 - one inch hex bits
- 3 - Phillips bits
- 1- 8" Magna-Tip screwdriver handle
- 1 - bench tray to hold the above materials
- 1 - plastic field case to carry all of the above
I wanted even more versatility for my kit and so added a 2.5" stubby
screwdriver handle for close in work and two torx screwdriver bits for scope
ring screws. The fact that I was able to easily add items to the standard kit
and configure it to my needs is a plus. To be honest, I can’t think of gun
adjustment or maintenance situation that calls for a screwdriver that this kit
couldn’t handle. It doesn’t get more versatile than that.
Quality - First, the kits are American made. This goes a
long way in my book. The magnetic tipped handle is particularly nice and it’s
the primary item that makes this kit different. That’s because it’s not the
little, wimpy, under sized type that’s usually found in most shooting kits, but
rather it’s a big, hand filling eight inches long with a beefy inch and a
quarter wide handle for lots and lots of grip and torque. It’s also virtually
unbreakable, and like the rest of the kit, comes with a lifetime warrantee. One
nice feature is the fact that the steel shaft is hex shaped to allow the
attachment of a small wrench to put even more torque on really tough jobs like
rusted screws. Can’t do that with a round shaft.
The big advantage of a magnetic handle is that the bits can be rapidly
changed in and out very, very easily. The magnet in the handle is no slouch
either. It’s strong enough to make it seem like the bits are literally being
sucked down into the receptacle on the end of the shaft. The bits almost seem to
leap out of your fingers when you put them on. Once they’re in place, they’re
not going to move either. To test the magnet’s holding power, I put on the
heaviest bit in the kit and whipped the handle as hard as I could in a downward
motion several times. The bit didn’t move at all.
Another advantage of a magnetic handle is the fact that when the bits
are attached, they become magnetized as well. This is very handy because small
screws won’t fall off the end of the screwdriver which makes screwing them on
much easier.
The bits themselves are hardened tool steel and are industrial grade
quality. This is not just a name. This means that they are actually made by a
supplier that also furnishes them to several manufacturers who run large, high
volume assembly lines. These bits are used in impact type power screwdrivers day
in and day out. Strength and durability are critical. Tool failure in high speed
assembly operations is not tolerated. I’ve got bits from another brand of kit
that get thoroughly messed up on a regular basis in high torque situations
because they were made from fairly soft steel. That hasn’t happened with the
Brownells bits, and I doubt if it ever could. However, if a bit somehow did
break or get buggered up, it’s backed by a no hassle life time warrantee. Just
call and they’ll send you a new one.
The Brownells bits for slotted screws are also perfectly hollow ground
for an exact true and square fit. As you know a standard, tapered screwdriver is
the absolute worst tool to use in a slotted screw. Why they still make them that
way is beyond me. In tough situations, they’ll cam out of the slot, and damage
to the screw head is the inevitable result. Even cheap, imported "hollow ground"
bits from third word countries can cause damage. Brownells points out that
inexpensive "hollow ground" bits are often off square and will put uneven force
on the screw which can result in damage or even breakage of the screw head.
Breaking off a screw head on your gun - now THAT would really ruin your day.
Compactness
- The kit comes in a hard ABS plastic case
that measures 4" X 8.5" which is held together with a snap type lid. Almost all
of the discount store bit assortments come on a large, open tray-like affair
that is good for displaying the wares but totally unsuitable for being packed up
in a range bag or backpack. The Brownell’s kit is somewhat bigger than other
similar kits but that’s because of the big, full sized eight inch screwdriver
handle. Slightly bigger in this case is not necessarily bad as there’s room
inside for a little bin to store spare hammer springs, scope screws, etc. The
plastic tray on the inside that holds everything in place can even be removed if
you want to keep the tools on your work bench. There’s also some extra recesses
in the tray for additional optional bits and for a stubby handle if you want to
customize your kit even further as I did.
In an impromptu experiment I dropped the closed case on the concrete
floor of my garage to see if the case would be damaged and if the lid would stay
closed. The case was dropped from a distance of about 5’ on the front and side
edges of the case. The lid stayed tight and there was no damage other than a
little minor scuffing. The reason I did this is because some time back, I
happened to knock a kit that I previously used off a shooting bench at the
range. The lip popped open and bits flew out all over the place. After a lot of
searching, I eventually found all but two of them - which brings us to our next
criteria.
Replacement Parts - Things, especially small things,
have a bad habit of disappearing from time to time. Unlike the cheap tool kits
in the discount stores, if you lose a bit, you don’t have to buy an entire new
kit just to get that one part. Brownells can easily replace anything in the kit.
There are also specialty bits available in metric sizes, extra thin blades for
really fine screws, anti cam out Phillips types, extra long Phillips, and even a
bit for Millet rear sight elevation screws, etc. There are also additional
handles available like the stubby I choose, a collet type, or maybe you’d like
one with a hollow handle to hold even more bits on the inside.
All in all, I really like this kit. It comes very, very close to my
concept of an ideal set. I only have one suggestion, and that is that they throw
in a # 15 torx bit that fits scope ring screws for Leupold, Burris, Weaver, and
others as part of the standard package. If they really wanted to get crazy, they
could also throw in the stubby handle previously mentioned as it’s ideal for
either close in work or for jobs not requiring any amount of force like
adjusting elevation screws on open rear sights. Even without the extras, this is
a four star product worthy of a place in every serious shooter’s range bag.
One last thought. If you’re into amateur gunsmithing, definitely take
a look at Brownells Super Kits. There are more bits in there than I thought
existed. What ever you do, call them at 800-741-0015 and order one of their
catalogs. It’s fascinatingly huge and only costs five bucks, which is refundable
with your first order. That’s a heck of a good deal.
