TRIGGERS and CROSSBOWS

I
’ve been heard to say quite often over the
years that you can take an average
performing rifle, put a great trigger in it, and
it can become a great rifle. I still feel that way. I
have proven my theory repeatedly over the years
working with “project” rifles. Let’s face it, even
the most average rifle made possesses a potential
for accuracy that is far better than the shooter
sitting behind it.
The same can be said of the crossbow. Yup, it’s
a bold statement. Some may call it downright
absurd; after all, it is a short-range weapon, at least
when it is employed for the hunt. However, I beg
to differ. The same principals that apply to the
rifle, in the case of triggers, can also be said of the
crossbow. That being said, let’s take a deeper look
into exactly what I base my theories on.
THE TRIGGER FACTOR
A popular term you may have read or heard over
the years when rifle accuracy was discussed
is “lock time”. What is lock time, you ask?
Lock time is the measure of time between
the disengagement of the sear surfaces of the
trigger, and the actual ignition of the primer and
subsequent firing of the bullet. The best rifle
makers all brag that their triggers have a “short
lock time”. But why do they do this? What is
so important about a trigger having a short lock
time? We will come back to that shortly, but since
this is only part of the equation, I’d like to roll out
the entire process, and then we can see the overall
picture, and just why a great trigger can make a
good crossbow a great crossbow.
TRIGGERS and
Part of the total equation when firing the rifle, or
the crossbow, starts with the shooters eye, telling
the brain “it’s a go”, then the brain telling the
muscles of the trigger finger to contract. This
is the start of the process and it is referred to as
“hand/eye coordination”. The end result being, the
string retention claws are tripped, pivoting clear
of the string’s path, releasing it to the mercy of the
limbs and cams stored energy. The entire process
(as broken down) can be measured in a short series
of milliseconds (one millisecond is 1/1000 of a
second).
CROSSBOWS
By Bradley Whiting
38
Fall 2013
What does all this matter you may ask at this
point? It matters more than anything else you will
consciously do to encourage accurate shooting
in the course of the shot sequence. Allow me
to explain why. At the precise moment when
your eyes signal your brain to tell your finger
to contract, you are dead on your mark, right?
Taking for granted that you have diligently sighted
in your crossbow and nothing else goes wrong,
your shot, if allowed to be literally instantaneous
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Fall 2013
39
TRIGGERS AND CROSSBOWS
to your brain’s go signal would be a perfect shot. Unfortunately,
it just doesn’t work that way.
When we refer to crisp, we mean instantaneous, or immediate,
translating into less milliseconds used in the overall process.
The lag time between the eyes telling the brain to tell the finger to
contract, the finger’s contraction time, coupled with the infamous
“lock time”, which is followed by the arrow launch and clear
time, add up to several milliseconds between that first impulse
to shoot, and the arrow actually clearing (breaking contact) the
barrel/rail into free-flight. It is in these precious milliseconds
where accuracy suffers the most. You see, within this incredibly
short span of time, the rest of your body—all your muscles and
bones—simply cannot freeze, or be still during this process.
Your heart beats on, and your brain is simultaneously sending
thousands (if not millions) of instructions to the rest of your
body during this short, but crucial time, when stillness is ever so
important. Yet regardless of all our conscious efforts to be still,
there is movement—miniscule yes; undetectable to the eye, yes;
but aim-affecting movement nonetheless. When this occurs, that
one precious moment when you were dead-on, ceases to exist
almost instantaneously. Couple this with the stress of a shot on
live game animals, which typically causes most if not all of us to
experience an accelerated heart and breathing rate. Throw in some
adrenaline, and it’s a wonder we can hit anywhere near the mark
we started out with when the eye told the brain ‘We’re good, do
it!”
Phase three is the “over-travel” and great triggers have very little
or none, while poor triggers can have excessive amounts. Perhaps
at this point you are asking why over-travel matters? The sear has
broken, the trigger has played its role in the shot process, so what
does it matter? Let’s combine the three phases into an overall
shot process and see how these three phases affect accuracy.
Okay, so why then, does a great trigger help this seemingly
helpless cause? There are three factors within the process of
pulling a trigger that play a huge role in the overall shot process
we just looked at. The function of the trigger, as it relates to
how accurate the shot will ultimately be, can be broken down
into three distinct phases: the “take-up”, the “break”, and “overtravel”. These three phases of trigger actuation play possibly the
biggest role in the shot process overall. Allow me to explain.
Each of the three phases either serve to take up time, or cause
what would be a smooth overall trigger actuation to become an
interrupted process, in which constantly changing forces must
be applied by the shooter. Let’s look at each phase of the trigger
actuation to see why and how it affects the accuracy of the shot
process.
Phase one is the “take-up”, or “creep” as it is sometimes
referred. Take up is the pre-travel that leads to the break, or sear
separation. Great triggers exhibit one of two possible acceptable
characteristics:
1.) They have minimal or no take up.
2.) They have a smooth, light, and consistent take-up.
Average or poor triggers in crossbows exhibit several undesirable
characteristics:
1.) They can be heavy.
2.) They can be gritty.
3.) They can be excessive in duration.
4.) They also can be a combination of any (or all) of the
three listed above.
Phase two is the “break”, or separation of the sear surfaces, which
causes the crossbow to fire. Great triggers exhibit low, crispbreaking poundage (a good range will be from 1.5 to 3.5 pounds).
40
THE TRIGGER EFFECT
When we look at the factors of the trigger actuation, or act of
pulling, we can identify two accuracy killers. The first is time,
and the second is the level of smoothness with which the process
is carried out. Simply put, time is our enemy—throughout the
process—from the time our eyes signal the brain until the arrow
is in flight. Time is precious to accuracy, and the less time taken
from start to finish serves to preserve that initial sight picture that
the eye decided was perfect.
The level of “smoothness” is yet another factor that can rob
accuracy. A smooth overall trigger pull elicits less opportunity
for movement of the crossbow during the shot sequence. This
is why great triggers exhibit no take-up, or a very light, even,
smooth take-up. So what about that over-travel we singled out
as an accuracy killer? How does that matter again? It matters a
lot and this takes us directly back to lock time. The time it takes
between the separation of the sear surfaces, and the actual release
of the string, has a set time factor in the sequence—and so does
the over-travel as both occur simultaneously. When the sear
surfaces disengage, if there is allowable over-travel, the natural,
uncontrollable reaction of the trigger and trigger finger is to
accelerate. This acceleration can again be the catalyst for more
unwanted movement. Now add the possibility of the sudden stop
when the trigger reaches its final back wall, and the accompanying
force applied by the trigger finger and we have even more
movement. The overall result is that there is movement of the
crossbow before the arrow actually loses contact with the barrel
track. If it affects a rifle bullet during it’s travel through a barrel at
3,000fps; it will occur even more so with a crossbow because it’s
firing at 300fps and that is a much slower process.
What can we do to defeat, or at least minimize all this movement?
Two things come to mind. We all know the first and best way:
practice, practice, practice! Practice creates muscle memory
and familiarity with the trigger. The more we practice, the better
we become at performing a smooth, shot sequence; it becomes
routine. A smoother shot sequence equals less movement. The
second way to defeat movement is to seek out a great trigger.
In the world of firearms, this is typically an easy thing to do.
There are several aftermarket trigger makers that are craftsman
at building triggers. Additionally, in the past few years many of
the big name rifle makers have begun to offer adjustable triggers
right from the factory—shooter adjustable to boot. However, we
are talking crossbows, which by nature have a much greater task.
Adjustable triggers, and shooter adjustable triggers may be on the
way, but I would be very careful from whom I would purchase
one. I would need to see a lot of data from the maker that clearly
proves an acceptable safety margin.
Fall 2013
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TRIGGERS AND CROSSBOWS
When assessing the industry as a whole, crossbow manufacturers
have made great strides in trigger quality. Manufacturers such as
TenPoint, Bowtech, Scorpyd, Darton, Parker, Barnett, Kodabow
(just to name a few) are producing better triggers with each new
model release. When we consider the difference between a rifle
trigger’s inherent circumstance, which is nothing more than
overcoming a light spring force that need only drive a firing pin
into a primer, we must salute the crossbow industry as a whole for
their efforts. We are seeing good results in the available trigger
technology!
Let’s face it, the crossbow industry is in a frenzied state. As I
write these very words, a dozen new items are hitting the market
with dozens more in development. Inevitably some will be good,
some bad, some just so so. However, once in a while, a product
comes along that can change the way we think about things.
Recently, the staff of Crossbow Magazine had the privilege of
being able to work very closely with an absolute industry “game
changer”: Trigger Tech. The Trigger Tech team has definitely
raised the bar for crossbow specific trigger mechanisms and the
staff here at CBM collectively feels, their trigger offering is the
new benchmark for the crossbow industry.
Like most great triggers, it must be experienced to be fully
appreciated. In addition to its excellent performance, it boasts
a safety factor the folks at Trigger Tech estimated to be five
times that of a standard factory trigger (for the factory models
it currently replaces). That is a huge improvement! My first
impression was simple amazement at the functionality of this
trigger. I’ve subsequently seen this same look in the eyes of
others when I watch them shoot with the Trigger Tech for the
first time—they are amazed. That being said, there is bad news
and great news. The bad news, for the time being anyway, is
that Trigger Tech’s trigger is currently only available as a drop-in
replacement for Excalibur and Middleton crossbows. The great
news, looking toward the future, is that the boys at Trigger Tech
are developing their proprietary mechanism for several other
makes and models as this article goes to the printer. Trigger Tech
is definitely leading the way in crossbow trigger technology and
we can’t wait to see where their ingenuity leads next.
With manufacturers designing triggers that are better with each
new model release, and companies like Trigger Tech introducing
new technologies that legitimately “raise the bar”; the future looks
brighter than ever for the crossbow. It is evolving into a more
accurate, safe, and highly effective hunting tool. Some may say
when they finish reading this article, “why bother?” Still others
will decide, “things are fine just as they are.” However, some
hunters want every advantage possible for that crucial moment
when that buck of a lifetime presents himself. In my mind,
possibly the biggest advantage you can have is a great trigger—
and this crossbow hunter is all for using the very best money can
buy!
Precise Trigger Control
High performance triggers
for crossbows
“ TriggerTech’s triggers are the single most
innovative new piece of equipment that has
come out for the last several years. Its
safety and precision is unmatched by any
crossbow trigger” Don Katsumi, Boo Custom Strings
www.triggertech.com
647-781-1723
[email protected]