It doesn't take a lot of cardboard to shoot 12-yard
patterns with IC and M choke tubes in the gun. At 12
yards the Improved Cylinder choke tube had a 14"
pattern and the Modified choke tube had a 13" pattern.
So into a circle the size of a medium pizza , we put a
couple hundred pellets (would you believe 359 No. 8's
in a 7/8 oz. 20 gauge load?). The small pattern makes
it easy to miss -- but then connecting with this
pattern ain't all it's cracked up to be either.
In theory, an Improved
Modified choke in a 20 gauge barrel is defined as
having a maximum of .007" constriction more than the
bore diameter. That's the theory, but you have to
understand that on production guns, you almost always
end up with more constriction than
advertised.
This error is compounded by
advances in the development of shotshell
ammunition.
Baschieri &
Pellagri, who is probably best known to bird
shooters for their 16 and 28 loads, markets a 12 and
20 gauge shotshell ammunition line which features the
Gordon System of ignition, that has helped B&P win
gold medals in competitive shooting. This probably
requires a word of an explanation because it
epitomizes the kind of creative thinking that
contributes to the efficiency of shotshell design and
usage today. You can learn more at: bandpusa.com.
The Gordon System is a
different way to make shotshells. The inner base of
the hull is a progressive dampening spring that
operates when the shell is fired. This has an
immediate benefit: it works along with a collapsing
base wad to absorb recoil by reducing operating
pressures. It's like having a shock absorber in front
and a recoil spring in the rear. The key benefit here
is that you can operate at lower pressures --
which translates into less shot deformation -- which
means better patterns and less recoil -- hence less
muzzle jump, so you don't have to look all over the
sky to take a pair. It means you can ratchet up the
shot speeds to buy an extra five or ten yards of range
&endash; say out to 30 or 35 yards when you have open
chokes in the gun &endash; without boosting operating
pressures or felt recoil.
What we have here is a
situation where we're pushing modern shotshell
miracles -- from B&P, Federal, Fiocchi, Remington
and Winchester -- through an arbitrary choke choice
that was designed for shotguns with half-inch forcing
cones, cardboard shells with fiber wads and chilled
shot in use a hundred years ago!
Briley to the rescue! While it
was still on the drawing board, BSA wisely decided to
use the semi-standard Beretta threading for their
choke tubes &endash; which meant that the BSA Royal
model test gun was able to benefit from Briley's
(800/331-5718) research and the development of their
Diffusion choke tube (a skeet choke tube, cut
with a one-turn-in-14" rifling). The idea is that the
rifling imparts a spin to the shot as it goes through
the tube en route to the bird. The following chart
shows how the Briley Skeet ($35) and Diffusion
($55) choke tubes compare to the BSA factory Improved
Cylinder chokes at 12- and 20-yard
distances:
|
|
Pattern
diameter (in inches) at:
|
|
|
12 Yards
|
20
Yards
|
|
BSA-supplied
Improved Cylinder choke
|
14"
|
22"
|
|
Briley Skeet choke
|
16
|
25
|
|
Briley
Diffusion choke
|
17.5
|
29
|
On 12-yard birds, Skeet choke provides a 14% larger
pattern; the Diffusion spreader tube, a 25%
larger pattern. At 20 yards, the larger pattern
bonuses remain pretty much the same -- about a 14%
larger pattern with Skeet and a 31% larger pattern
with the Diffusion spreader choke.
Write this down: you
will take more birds with open chokes!
You
and the 12 Yard bird - Part I