Enter your e-mail address here. Why subscribe to Midwest Whitetail?
Eliminating Human Error
Posted By Bill Winke at 3/28/2011 12:00:00 AM
20110328094750592.jpg
A shooting machine will help you eliminate
human error when setting up a bow.
Shooting machines are the very best product testers because they eliminate archery’s most difficult variable: human error.  After removing human error, here is what shooting machines have taught us about how we need to shoot a bow.  There is so much to talk about that I am going to produce this blog in two parts.  This is part one.
 
DRAW LENGTH FORGIVENESS 
  
Every bowhunter has a zone in which he anchors.  In bows with a wide valley and soft back wall, it may actually be more than half an inch long.  In bows with short valleys and hard walls, it is less.  That is why many of today’s best bows have rock solid back walls - and why I recommend only these bows.  
  
On days when he is feeling strong, the archer pulls the string until the cams roll hard into the wall.  On days when he is distracted or tired he may ease into the middle of the letoff valley where he can use the friction in the cams and cable slide to increase the bow’s effective letoff.  Such a small change in form doesn’t seem like a big deal.  We all do it, right?  Well, the best shooters don’t, and there’s a good reason.  They’ve learned through actual shooting the same things that a shooting machine now teaches.  How far you pull the string makes a huge difference in impact.  
  
When you pull the string back slightly farther or shorter than normal, you change the relationship between your eye, the pin and the target.  The riser tips a little when you pull back farther or less than normal.  The sight is not accurate anymore.  It has to do with the geometry of the bow. 
  
Bow’s with very solid back walls at full draw are easier to shoot consistently than those with soft back walls.  You can pull up against the wall gently and it stops the draw in the same place every time. 
  
20110328094805708.jpg
Pull firmly into the back wall at full draw on every shot you take.
In some cases, you can make a two-cam or hybrid-cam bow more forgiving of draw length variations by setting the bottom cam slightly “behind” the top cam.  In other words, it gets to its full draw position just a fraction later than the top cam.  You do this by first setting the cams so they are perfectly timed and then letting out one or two twists (making the harness longer) on the harness attached to the top cam.  It may not work in all cases, but it is a common way that top shooters set up their bows.
 
ALL BOWS ARE NOT CREATED EQUAL 
  
I’ve always felt that all bows were accurate in and of themselves.  You could put any bow into a shooting machine, regardless of brace height, axle-to-axle length, weight, cam style, etc. and they would all shoot exactly the same once tuned and sighted in.  In other words, I felt that a bow was critical only in the way it interacted with human form.  I was wrong.  Some bows are more consistent than others. 
  
The most common source of inconsistency is the string and harness system.  As they stretch, they change the draw length and possibly the bow’s timing and nock travel.  As already mentioned, any changes in draw length that occur without the bow being re-sighted can result in major accuracy problems.  Serving separation is another result of string stretch.  As the serving separates, the nock point moves up and changes the arrow’s flight and impact dramatically. 
  
20110328094746504.jpg
To maximize your consistency, you need a high quality string and harness
system that won't stretch, and you need to take care of it.
To combat these problems, use a high quality string and harness system.  I’ve been using the Fuse strings and harnesses (they come standard on Hoyt bows) and they have maintained their length very well over the past three years.  Regardless of which string and harness system you use, just make sure it is very stable – without any stretch – or your bow will become less consistent with time. 
 
CONCLUSION 
  
Shooting machines have shown that bows are very sensitive to how far they are drawn and the way in which you approach your anchor point.  Make sure to always buy bows with solid back walls and pull the string solidly into the wall on every shot.  
  
20110328094812385.jpg
How far you pull back the string will affect your accuracy.
There are also steps you can take to make your bow more forgiving.  First, you can set the timing of the top cam of a two-cam or hybrid-cam bow slightly ahead (reaches full draw first).  You can also buy the best string and harness system you can afford in order to eliminate the variables related to stretch.  By simply taking these steps you’ll be amazed by how much better you will shoot. 

In the next blog I’ll discuss how arrow flight is affected by nock travel and cam tilt.  I’ll delve into the question of whether or not a bow can be un-tunable.  Is your bow a lemon?  I’ll help you find out.  
  
Hooter Shooter shooting machines are available from Spot-Hogg.