Choosing Your Arrow Length

Many shooters believe that proper arrow length should always be equal to or should exceed the bow's draw length.  So if we rely on this conventional wisdom, a 30" draw bow would always shoot a 30+" arrow.  Right?   Well......not necessarily!!!  Times have changed, and the traditional thinking may or may not apply to your particular bow rig.  In many instances, the proper arrow length for your bow may be considerably less than the measured draw length of the bow.  

RISER TYPE:

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.  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, where a cutaway riser generally cannot. 

So what does all this have to do with arrow length?  Ah-ha!  Remember our earlier discussion where we learned "If you drew back a 29" arrow, and the insert of the arrow lined-up with the front edge of the bow's riser, the bow is set for approximately 29" draw length"?  Hold that thought.  Because center-shot cutaway risers can shoot arrows that are LESS than the bow's adjusted draw length (so they can rest inside the arrow shelf).  Bows without a center-shot cutaway riser generally cannot (arrows must "hang-over"). 
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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, 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.  In fact, many modern compound shooters trim their arrows to the minimum length - just beyond the arrow rest.  Why would they do that?  Simple....SPEED!   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 Section #4.  But ultimately, the position of your arrow rest determines the minimum arrow length for a modern center-shot cutaway bow.  An arrow that is trimmed 1/2-1" beyond the arrow rest will work quite well in a center-shot cutaway riser bow. 
 

ARROW REST POSITION FOR 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 necessary arrow length.  With a standard TM Hunter style rest, the proper arrow length is usually 1-2" less than the bow's draw length.  With a Whisker Biscuit rest, usually 2-3" less than the draw length.  And with a Muzzy Zero Effect, as much as 3-4" 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.

                   
With all that said, the most reliable method is to actually draw back an arrow and measure.  Once your draw length is set perfectly and your arrow rest is mounted in it's permanent position, you can simply draw back an arrow and have someone else use a magic marker to mark the shaft where it actually sits on the arrow rest at full draw.  Trimming the arrow shaft anywhere 1/2" (or more) forward of that position is acceptable.  The most common method is to trim the arrows so that 1" sticks out beyond the rest.  We recommend you not trim arrows to the very bare minimum, as over time your string may stretch a little, letting your draw length out a tad, and leaving you with arrows that are too short.  And once an arrow is cut too short, it's cut too short for life.

ARROW LENGTH AFFECTS ARROW SPINE:
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.

Note :  Yes!  We realize static spine and dynamic spine aren't the same thing.  We'll get to that too.  :)
 

To Cut or Not to Cut:  Trimming the Arrows

When you purchase your new set of arrows, you have two choices regarding arrow length.  Most raw arrow shafts are deliberately made too long (usually 32-24") so that they can be trimmed to length to suit your particular 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.  Metal inserts are often installed with a "hot-melt" type glue to allow fine tuning of some style broadheads.

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 just need to screw in your tips and then you're all ready to shoot.  However, before you select this option, you should double-check your measurements for accuracy.  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, in certain circumstances, full-length arrows, still uncut and without inserts installed can be returned. 
 

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 less 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. 

Arrow Weight:  Laws & Warranties

CHECK THE LAW  

Years ago, 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.  And in fact, the same manufacturers who once attacked the carbon arrow concept NOW make their own carbon arrow shafts to sell. 

Fortunately, 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 example: Washington State bowhunters must shoot arrows that weigh at least 6 grains per pound (rather than the 5 gr/p/p 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 law and be sure your equipment is in compliance from season to season.

WARRANTY SNAFU

Virtually all manufacturers rate and advertise their bows' IBO SPEEDS using test arrows that weigh exactly 5 gr/p/p (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/p/p.  But 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 on us.    

To save a few dollars in warranty repairs and (more publicly) to increase their margins of safety, a few manufacturers will sneak in a 6+ gr/p/p 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 factory recommendation. 

If you have an older bow, or received no documentation with your bow regarding arrow mass, contact the manufacturer before shooting lightweight carbon arrows.
 

Chapter #2 Complete
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