CHAPTER 2: Arrow Length,
Straightness, and
Mass
Proper Length of an Arrow
Safety first! Arrows that are too
short for your bow setup are a serious hazard. Even an
arrow that is just long enough is too short. The
best safety practice is to make sure your arrows sit at least 1"
forward of your arrow rest when the bow is at full draw.
A little bit of extra arrow length gives the arrows an important
margin of safety. An arrow that is too short can lodge
behind the arrow rest at full draw. If this happens
and you don't notice it before you fire the bow, the arrow could
buckle and snap upon release ... possibly sending shards of
carbon into your bow hand or arm. This is called an
obstructed path shot ... which is a very very bad thing.
See our
Arrow Safety Warning page for the gruesome details.
Unfortunately, some shooters (and shops) deliberately cut
arrows too close to the arrow rest, usually to minimize arrow
mass and get the fastest possible arrow speeds. But this
practice regrettably comes at the expense of safety. The extra
1-2 fps you gain by cutting arrows "just long enough" isn't
worth risking an arrow shaft stuck in the forearm. So
never shoot arrows which are too short.
On the other hand, shooting an excessively long arrow isn't so
smart either. If your arrow length is excessive, your
arrow will have additional (and unnecessary) mass and the
additional length will increase the arrow's spine requirements
(more on this in
Chapter 3).
Basically, extra long arrows significantly decrease your arrow
speeds and limit the performance of your bow.
So choosing a safe yet optimally performing arrow length is
very important. If you have a modern center-shot cutaway
riser bow which is already setup, finding your optimal arrow
length is easy. Simply draw an arrow back to full draw and
hold, while another person (safely standing to the side of
course) takes a Sharpie marker and makes a mark on the arrow
approximately 1" forward of the arrow rest. Then measure
the arrow from the groove of the nock (like in
Chapter 1)
to the mark on the arrow, and you've got it.
Unfortunately, this doesn't apply to everyone ... especially
those with older bows or traditional bows. So let's look
at this in more detail.
Arrow Length Misconceptions
Some archers believe proper arrow length should be equal to
bow's draw length. This is a dangerously incorrect
rule-of-thumb. In some cases, proper arrow length may
equal the bow's draw length. But modern compound bows tend
to require less arrow length, while older compound bows and
traditional bows require more. So DO NOT assume your draw
length and proper arrow length numbers directly correspond.
In most cases they will not.
Bow Type & Riser
Style Considerations
There are several factors to
consider here. So we'll start with the big one - riser type
(the riser is the "handle" portion of the bow). Some years ago,
as traditional magnesium molded risers gave way to the
production of CNC machined aluminum, we were blessed by the
welcome innovation of the center-shot cutaway riser (Figure A).
The center-shot cutaway riser has a much wider arrow shelf, and
the center section of the riser is shifted well to the side.
This allows the true center-shot of the bow (where your arrow
rest should line up left and right) to be spaced far enough away
from the riser's edge as to allow feathers and vanes to easily
pass by the inside edge without any contact with the bow. A
brilliant idea! Almost all new compound bows are now this
style.
A basic molded riser (Figure B) does not have this feature. If
you have an 80's or early 90's vintage bow, you almost certainly have this
type of riser. In a non-cutaway bow, the actual
center-shot of the bow is very close to (if not right against)
the edge of the riser. This type of riser typically uses a
flipper/plunger style rest mounted right against the side of the
bow, where a cutaway riser generally cannot.
It is important to identify what type of bow you have. If
you have a modern cutaway bow (Fig A), your proper arrow length
is often less than than the bow's AMO draw length. If you
have an older non-cutaway bow (Fig B), your proper arrow length
will be more than the bow's AMO draw length.
Clearance for
Broadheads

With
a traditional molded riser bow, arrows must be AT LEAST as long
as the bow's draw length if you ever intend to use broadheads or
other tips larger than the diameter of the arrow. Since the
arrow rides along close to the riser, there isn't enough room to
draw back a broadhead over the arrow shelf such that one of the
blades doesn't snag on the edge of the riser as you're coming to
full draw. So if you have an older bow without the benefit of a
center-shot cutaway riser, choosing your arrow length is easy.
In this case, we recommend you order arrows 1/2-1" longer than
the bow's actual adjusted draw length. And regardless of what
kind of riser you have, if you intend to shoot specialty small
game hunting tips (Judo Points, Snaro's, Condor Tips, Turkey
Guillotine Heads, etc.)
which are unusually wide, you will definitely need arrows that
are slightly longer than the bow's draw length. Even a
center-shot cutaway bow doesn't have sufficient clearance to
draw that type of tip beyond the outer edge of the riser.
Now, if you shoot a modern bow with a center-shot cutaway riser,
the choice isn't so simple. Since a center-shot cutaway riser
allows clearance for common broadheads to be drawn back beyond
the outer edge of the riser, you can shoot a considerably
shorter arrow. The shorter an arrow is, the lighter it will be
and the faster it will fly. We'll discuss the issue of arrow
weight vs. speed in much more detail in
Chapter 5.
But ultimately, the position of your arrow rest determines the
minimum arrow length for a modern center-shot cutaway bow. In
most cases, trimming your arrows 1-1.5" beyond your arrow rest
will make for an ideal arrow length on your modern cutaway bow.
Arrow Rest Type &
Position on Cutaway Bows
Some arrow rests mount more rearward than others, permitting the
use of shorter and shorter arrows. There's even a device known
as an overdraw, that's specifically designed to relocate
and reposition the arrow rest rearward - just so a shorter arrow
can be used. However, with the increasing popularity of
lightweight carbon arrow shafts, overdraws aren't really
necessary any more, and are rarely used on modern hunting rigs.
But some type of modern arrow rests still function much like an
overdraw - locating the rest position closer to the shooter.
The diagram below illustrates how the position of the rest
changes the bow's necessary arrow length. With a standard TM Hunter
prong style rest, the proper arrow length is usually 1-1.5" less than
the bow's draw length. With a Whisker Biscuit or similar rest
which mounts just behind the riser, proper arrow length is usually
1.5-2" less than the draw length. And with a Muzzy Zero Effect
or other far-rearward mounted rest,
proper arrow length can be as much as 2-2.5" less than the bow's draw length. However, it
should be noted that most arrow rests can be mounted and
adjusted in different positions. Consider this as an estimation
only.
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Again, the most reliable method is
to actually draw back an arrow and measure (as described above).
Once your draw length is set perfectly and your arrow rest is
mounted in its permanent position, determining your optimal
arrow length is easy. But if you don't have a field-ready
bow to measure, you can make a reasonable estimate based on the
bow's draw length and type of arrow rest installed.
Remember to error on the side of caution. In one way, a
new
arrow is like a new 2x4. One that's a little long can always
be shortened - but not the reverse. Once you cut a stock
length arrow, the deal is done. Custom carbon arrows are
not returnable to stores. Once the arrows are trimmed to
the length you specify, they're forever yours.
Arrow Length Affect
Arrow Spine (stiffness)
Before you make up your mind about your arrow length, there's
one more detail we'll need to consider. The length of your
arrow is a factor in determining the proper stiffness, or
spine, for your perfect arrow. The longer your arrow
is, the more limber it will act when shot. The shorter your
arrow is, the more stiff it will act when shot. We'll cover
this issue in more detail in the next section, but you should be
aware that shooting an extra long arrow often results in a
double-whammy regarding arrow weight. If you shoot an
excessively long arrow, not only will the excess shaft weight
result in a heavier and slower flying arrow, but the added
length may necessitate changing to an even heavier/stiffer arrow
spine. For those of you looking to bulk-up your carbon arrows
to gain a little KE (more on this later too), a little more
arrow length may be a good thing. But most shooters want to get
as much snap as possible out of their high performance compound
bows, so keeping an eye on excess arrow weight is a big
consideration.
Nitpicker's
Note : We realize static spine and dynamic spine
aren't the same thing. We'll get to that too. :)
Choosing to Trim Your
Own Arrows (option)
When
you purchase your new set of arrows, you have two choices
regarding arrow length. Most raw shafts come in stock-lengths of
32-34", so that they can be trimmed to
make a proper AMO length arrow to suit virtually any bow. You may choose to
receive your arrows UNCUT (full-length) OR you may receive your
arrows already trimmed to length and inserted. There is no added
charge for trimming and inserting your arrows, but here are a
few things to consider before you decide.
Carbon arrows should only be cut with a high-speed
abrasive-wheel saw. Attempting to trim your new carbon arrows
with your hacksaw or your plumber's tubing cutter will result in
splintered fibers and a weakened arrow shaft. Using a good
quality arrow saw is best. However, with a little patience, you
can get a respectable cut using your Dremel Rotary Tool with an
abrasive cutting wheel attachment. So if you're the "handy"
type, you may wish to order arrows full-length and trim your
own. Metal inserts will still be included (but uninstalled) with
full-length arrow orders.
If you would rather avoid the handyman hassle and you're already
sure of your arrow length, we would be happy to professionally
trim and insert your new arrows free of charge. In this case,
once your arrows arrive, you'll be ready to shoot as soon as you
open the box. We even include practice tips installed in
every arrow. However, before you select
this option, you should double-check your measurements for
accuracy. Again, it's always safer to measure twice and cut once, as
once your arrows are trimmed to the length you specify, they
cannot be returned for an exchange or refund. However,
unaltered full-length arrows, still uncut and
without inserts installed can be returned.
Arrow Straightness
and the ±.00$ Factor
Most carbon arrows are advertised to have a specific
straightness tolerance between .001" and .006". The straighter the arrow,
the more expensive they will typically be. Before we get
too deep into this topic, it's worth noting that there doesn't
seem to be an accepted universal method for HOW arrow
straightness is measured. Per ATA/ASTM standards, arrow
straightness should be measured along the full length of the
shaft minus two inches. But as we understand it, this
is NOT how things actually go inside the industry. On a
number of occasions, we have heard arrow companies accuse each
other of cheating their straightness measurements -
either by measuring only short sections of their arrows, or by
obtaining their straightness numbers via undisclosed measurement
methodologies. If you
think the bow business is cut-throat, you should witness how the
arrow companies go at it behind closed doors. To avoid
being shanked at the next trade show, we'll stay neutral, and
assume that everyones' arrow straightness numbers are reasonably
honest and comparable.
With that said, let's examine the typical straightness "classes"
of arrows. Most standard-grade
carbon arrows have an advertised straightness of .005-.006".
These shafts are usually marketed exclusively to the hunter and
beginning archers. For the purposes of big game hunting
and general target use, standard-grade shafts are more than
adequate. A typical human hair is about .004"-.006" in diameter.
So even a basic carbon shaft of .006" straightness is quite
good, and straighter than you could possibly perceive without
specialized equipment.
But ... making and selling arrows is a very competitive
business. So most arrow shaft manufacturers also
offer a mid-grade shafts which will have an advertised
straightness of around .003-.004", and "pro" grade shafts
claiming a straightness of .001-.002". And as you might
expect, these premium grade arrows fetch a premium price.
If you're the kind of buyer who always goes for the good
stuff, then by all means, buy the straightest shaft you can
find. But before you shell out the green for a ±.001
shaft, there are couple things you should know.
First,
the difference in a ±.006" shaft and a ±.001" shaft is
more razor-thin than you might think. Carbon arrow shafts
are constructed by taking very thin layers of carbon sheets and
rolling them up into perfectly straight tubes (usually 6ft. long
or so), much like you might roll-up a big map. Once wound,
the carbon tubes are then heat-treated to bond all the layers
together. When the heating process is complete and the
carbon tubes cool down to room temperature, they are cut into
sections (raw shafts). Some of the shafts, particularly
those that come from the center of the roll, retain their ±.001"
straightness while other sections distort slightly from the
heating/cooling process.
As we understand it, the results vary from run to run and day to
day. In most cases, even the manufacturer doesn't know how
the day's crop of shafts will come out. But once the
shafts are made, the manufacturer measures the straightness of
each shaft and sorts them accordingly for banding and sale.
One sort may be named and marketed as one arrow, another sort as
something else. For example, the Beman Bowhunter ±.006" @ $64.95 p/dz
and the Beman ICS Hunter ±.003" @ $89.95
are just two different sorts of the same shaft - same raw
materials - same construction technique. Same is true for
the popular Gold Tip Expedition ±.006", Gold Tip XT ±.003", and the
Gold Tip Pro ±.001".
They're literally cut from the same cloth.
Small variations in the daily manufacturing environment
(humidity, pressure, air convection patterns, etc.) along with
tiny deviations in the characteristics of the raw materials
ultimately determines the straightness of the finished product.
On one particular day, the manufacturer might yield an entire
batch of
±.001" shafts, or an entire batch no better than ±.006", or even
a mixed bag of straightnesses, all from the very same processes
and materials. The finer tricks of the trade are carefully
guarded secrets, as the art of consistently building straighter
arrow shafts is literally a technical exercise in splitting
hairs. But make no mistake, arrow manufacturers would
rather avoid the ±.006" days. The more ±.001"
days a manufacturer has, the more money they can make.
Why? Because straighter shafts, whether they cost more to
manufacture or not, are worth more in the marketplace. So
don't be fooled into thinking that your set of $129 ±.001" pro-grade
shafts are somehow fundamentally better constructed, stronger,
or made from finer materials than a basic $69 a dozen ±.006"
hunting shaft. In most cases, they're just a few
thousandths of an inch from being the exact same product.
Straighter Arrows
Shoot Straighter, Right?
From
a pure physics standpoint, yes! Arrow straightness
certainly does matter. Straighter arrows undeniably fly
more accurately. In long-range laboratory conditions with
a mechanical shooting machine, the straightest arrows with the
best spine consistencies will always group best. But try
to keep this issue in reasonable perspective. You are not
a mechanical shooting machine. You don't shoot in
laboratory conditions, and you probably don't shoot at extreme
distances (100+ yards). The straightness difference in a
±.006" arrow and a ±.001" arrow is literally the width of a
single human hair. So realistically, the ±.001" arrow
probably has more to do with selling arrows than shooting
arrows. The truth is, only a handful of the world's
archers actually have enough shooting skill to differentiate
between a very good ±.003" arrow and a "pro grade" ±.001" arrow.
And within the typical bowhunting range, any difference would be
practically imperceptible.
Nonetheless, bowhunters tend to attribute their successes or
failures to their equipment rather than to their actual skills.
So owning and shooting a set of professional grade ±.001"
arrows may provide some bowhunters with an edge in confidence, even
if the actual technical advantage is negligible. If you're
one of the many archers who
believe that success is only one more purchase away,
buy whatever arrows you like. Just remember that
super-straight arrows won't correct poor shooting form. In
the end, the
benefits of a good practice regimen and proper bow tuning will
FAR outweigh the benefits of shooting expensive arrow shafts.
Are Carbon Arrows
Straighter than Aluminum Arrows?
Yes and no. While a carbon arrow's advertised specs may be
no straighter than a typical aluminum shaft, carbon arrows
resist distorting and "bending out of shape" much better than
aluminum arrows. Though an aluminum shaft may BEGIN with a
similar ±.003" straightness, its straightness quickly
deteriorates through normal use and handling. So after a
few months of use, your aluminum arrow set may contain a few
arrows that are at original specs and some that are grossly out
of straightness. Carbon arrows generally do not retain this kind
of "memory" after being stressed (bent). So your carbon arrow
set stays much more straight and uniform - even with heavy use.
Some archers even joke that there are only two states of a
carbon arrow: straight or broken, but never bent. While that's
not entirely accurate, it does help to illustrate the point.
Arrow Weight:
Grains not Grams
The
actual weight of your finished arrow is also very important.
Arrows which are too heavy
will fly too slowly and with too much loss of trajectory.
Lighter arrows fly more quickly, but arrows which are too light
can damage your equipment. So you'll need to know a thing
or two about arrow mass and industry safety standards. How heavy should your arrows be?
Well, let's start at the top.
First thing ... the weight of an arrow (as well as projectiles
in most shooting sports) is customarily measured in
GRAINS. Grains (gr) and grams (g) are totally different units
of measure. So don't confuse them. The grain is a British system unit - based on the
weight of a grain of barley. A gram is an entirely
different unit of measurement. So let's just try to just forget
about grams for now.
A grain is very small unit (only 1/7000th of a pound), so if you would like to have
the ability to accurately weigh your own arrows, you'll need a
specialized scale. You can purchase an
archer's scale that's specifically calibrated in grains for
under $50.
However, when you order custom arrows from Hunter's Friend, your
arrow set will arrive already weighed and certified by one of
our professional arrow builders.
Are Lighter Arrows
Better?
This is a hotly debated topic that we'll cover in more detail in
Chapter 5.
But the fact is, lighter arrows fly faster with less loss of
trajectory. A faster arrow won't necessarily penetrate
better, but it will make it to the target more quickly.
For some bowhunters and 3D shooters, this is a great benefit.
A bow that shoots very fast is often described as "shooting
flat." The "flat" part is a reference to the natural
rainbow-shaped parabolic flight-path that all arrows invariably
take. A faster arrow travels with less perceptible arc, so
it is described as shooting "flat," although "flatter" might be
the more accurate word. Either way, a fast flat-shooting
arrow is something many shooters seek in a bowhunting or 3D rig.
In the current archery market, speed sells. Right or wrong, it's a
fact. Like in many industries, archery manufacturers are under constant
pressure to make things go faster. As a result, each year brings a new
bumper-crop of even lighter arrow shafts, better string materials, more
efficient bow designs, friction-reducing components, etc. Again, there
is some disagreement on this issue, and we'll hammer out the pro's and
con's in Chapter 5,
but the main idea is, lighter arrows go faster -
sometimes dramatically faster. Heavy arrows go slower. So if you want
your bow to shoot "flat," lightweight arrows are going to be a must.
Is there a Limit?
How Light is Too Light? Shooting an arrow that is
too light can be dangerous, both to you and your expensive compound
bow. Shooting an underweight arrow has a similar effect as dry-firing
your bow. Without sufficient arrow weight, the string and limbs of your
compound bow move too quickly and violently. It's like putting your car
in neutral and flooring the gas pedal. The bow needs the resistance of
the arrow to slow it down - so it doesn't "rev" out of control.
Of course, an underweight arrow will fly like a rocket - generating
unbelievable speeds. But anyone who does this is just asking for
trouble. Modern compound bows aren't toys. They generate a tremendous
amount of energy and should be treated with the same respect you would
give any dangerous weapon. The vast majority of serious compound bow
failures are not caused by manufacturer defects, but rather by
dry-firing the bow or shooting dramatically underweight arrows. For
your personal safety, and the longevity of your bow, we strongly
recommend you follow the IBO or AMO Standard regarding minimum arrow
weight.
The
International Bowhunting
Organization (IBO) sets a 5 grains per pound standard that's pretty
simple to follow. Arrow weight should never be less than 5X the bow's
draw weight. So a 60# bow should shoot no lighter than a 300 (5 x 60)
grain arrow. Simple enough! Another authority in the archery industry,
the Archery Trade Association (formerly the AMO), also publishes an
arrow weight recommendation chart called the
AMO Minimum Arrow Weight Chart. The AMO chart is a bit more complex
and takes more variables into account (brace height, bow efficiency, cam
design, draw length, etc.), but it is less widely used. Some
manufacturers ask you follow one standard, some the other. And
depending upon your particular bow setup, the IBO and AMO
recommendations may or may not be the same. Check the literature that
came with your bow to find which standard you should follow.
However, since the IBO Standard applies at most 3D courses, many
competitive shooters setup their arrows to weigh exactly 5 grains per
pound. This keeps them just within the rules while providing the
fastest possible arrow speeds. However, bowhunters usually choose arrow
weights between 5 and 9 grains per pound. Later on in this guide we'll
use an online arrow weight calculator to build a simulated set of
arrows, so you can make sure that your arrows will be the appropriate
weight for your bow before you actually order them.
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IBO
STANDARD: Minimum Allowable Arrow Weight - Includes Tip
Weight |
|
80# Bow |
400 gr min. |
64# Bow |
320 gr min. |
48# Bow |
240 gr min. |
|
78# Bow |
390 gr min. |
62# Bow |
310 gr min. |
46# Bow |
230 gr min. |
|
76# Bow |
380 gr min |
60# Bow |
300 gr min. |
44# Bow |
220 gr min. |
|
74# Bow |
370 gr min. |
58# Bow |
290 gr min. |
42# Bow |
210 gr min. |
|
72# Bow |
360 gr min. |
56# Bow |
280 gr min. |
40# Bow |
200 gr min. |
|
70# Bow |
350 gr min. |
54# Bow |
270 gr min. |
38# Bow |
190 gr min. |
|
68# Bow |
340 gr min. |
52# Bow |
260 gr min. |
36# Bow |
180 gr min. |
|
66# Bow |
330 gr min. |
50# Bow |
250 gr min. |
34# Bow |
170 gr min. |
Arrow Weight:
Fish & Game Laws
When carbon arrows were first introduced in the archery market,
their critics (mainly competing manufacturers who didn't make
carbon arrows at the time) launched anti-carbon arrow
advertising campaigns to dissuade archers from giving up their
heavy aluminum arrows for lightweight carbon shafts. These
ad campaigns claimed carbon arrows were dangerous, they would
splinter and break, they were inaccurate, wouldn't penetrate
well, they would ruin your meat, they could cut your hands
during field dressing, etc. Of course, as we soon learned,
all that corporate blathering was a distortion of the truth -
and today carbon arrows continue to command an increasingly
dominant share of the hunting arrow market.
The carbon arrow concept has prevailed, but there have been
casualties in the Aluminum vs. Carbon War. Several states still have
hunting laws that reflect the early misconceptions about using
lightweight carbon arrows for big game hunting. For examples: Washington
State bowhunters must shoot arrows that weigh at least 6 grains per
pound (rather than the 5
gr/lb recommended by the IBO), Alabama
bowhunters must shoot at least 100 grain tips in their arrows, and
Connecticut bowhunters must use arrows that weigh at least 400 grains
regardless of their bow's draw weight. And while these antiquated
restrictions may not exactly warrant an uprising, they are a part of
each state's effort to ensure ethical bowhunting practices. So we
strongly suggest you check your state regulations before ordering your
hunting arrows, and respect your state's rules and regulations. And be
advised that your state's rules and regulations may change from year to
year. As a sportsman, it's your responsibility to know the
(current) law and be
sure your equipment is in compliance from season to season.
Arrow Weight:
Manufacturer Warranties
Virtually
all manufacturers rate and advertise their bows'
IBO SPEEDS using test arrows that weigh exactly 5
gr/lb
(IBO standard). And if you
want to make your bow shoot even close to it's advertised IBO
speed, you have to setup the bow to shoot at or near 5
gr/lb.
So it would be logical to conclude that every bow manufacturer
accepts 5 gr/lb as the minimum safe arrow weight. But
this isn't necessarily the case.
Look at the photo on the left. How could this 70# bow ever
shoot close to it's 300 fps IBO speed if the manufacturer
clearly marks the bow to require a minimum 420 grain arrow?
Odd, eh? This kind of manufacturer recommendation is kind of a
marketing paradox. What they're saying is, "This bow can shoot
300 fps with a 350 grain arrow ... but YOU aren't allowed to
make it shoot that fast." As ridiculous as that sounds, several
manufacturers pull this little fast one.
To save a few dollars in warranty repairs and to
pad their liabilities should a catastrophic failure occur, a few manufacturers will sneak
in a 6+ gr/lb minimum recommendation on their limb sticker or
in their manual. Tricky, tricky! And some people follow it;
others ignore it. But with all that said, if your bow has such
a notation for heavier arrows, we suggest you contact the
manufacturer to question the warranty implications before
shooting arrows lighter than the official minimum. In all
other cases (modern compound) a 5
gr/lb minimum is probably
safe to assume.
Chapter 2 Summary
Before moving on, you
should be clear on the following:
1. What type of riser does my bow have?
2. Can I shoot an arrow that is SHORTER than my bow's draw
length?
3. Does my arrow rest function as an "overdraw", allowing the
use of shorter arrows?
4. What is the minimum safe arrow length I can shoot in my bow?
5. What are the only proper ways to trim a carbon arrow?
6. Can I return arrows which have been trimmed to length?
7. What level of arrow straightness do I need?
8. What is the IBO Standard regarding total arrow weight?
9. What is the minimum arrow weight my bow can safely shoot?
10. Does my state have any specific hunting restrictions on
arrow weight?
11. Does the manufacturer of my bow make any specific
recommendation regarding arrow weight?
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