Written by: Kim Lockhart, Copyright.
Shooting and Tuning A Crossbow For Accuracy:
Crossbow Fact: The crossbow's high precision appeals to those who love accuracy and accurate shooting equipment, myself included. Bench rest rifle shooters love the crossbow's ability to put each and every crossbow arrow, shot after shot in nearly the same hole at 40 yards, consistantly.
If your crossbow is not displaying this much accuracy then you need to read this for sure. Crossbows are very accurate when set-up and shot properly.
The first thing you want to do is check and make sure everything is good and tight, sights, scope, limbs, bow is still attached to stock, and be sure to check the flight rail, track, barrel for gouges, debris anything that may interfere with arrow flight.
Crossbow Arrow Selection:
1. To get the highest degree of accuracy from your crossbow the one thing without a doubt, is, an extremely well tuned crossbow can not shoot a bad arrow accurately this one thing can not be over-looked.
2. A crossbow arrow is short thus harder to stabilize its flight so 5 inch long fletching is highly recommended when looking for consistant accuracy.
3. Aluminum arrows bend quite easily, with just a few thousandths of bend you may not detect it with your eye so always check your arrows for straightness.
4. Because of the extreme acceleration from a high poundage crossbow I highly recommend carbon arrows as they do not bend or oscillate as readily as aluminum crossbow arrows, my own personal preference after much testing is the new "Beman ICS LightningBolt".
Reading and Understanding Your Crossbow Arrow:
The groove in the flight track of your crossbow will leave telltale marks on your crossbow arrows that you can read and understand if there is an accuracy issue with your current arrow selection as well.
1. If your arrow has heavy groove marks at the front of the shaft, this is a good indication that your arrow point selection is to heavy and the arrow is oscillating badly causing scattered grouping of arrows on target.
2. If your arrow has heavy groove marks at the rear of the shaft, this is a good indication that your arrow point selection is to light and the arrow is drifting badly causing scattered grouping of arrows on target.
3. If your arrow has heavy groove marks at the front and rear of the shaft, this is a good indication that your arrow is simply to light for your crossbows acceleration factor and you need to switch to a heavier shaft, again the arrow is oscillating badly causing scattered grouping of arrows on target.
4. If your crossbow arrow is lightly grooved marked from front to rear lightly marked toward the center of the shaft most likely you are shooting a good arrow and point weight for your crossbow.
Crossbow Scope Issues:
If you are using a scope that has magnification properties, is the scope parallax adjusted for the distance you are shooting.
Crossbow Shooting To The Left or Right, No Crosswind:
Why is it that all crossbows just don't seem to have the same accuracy potential. Mechanically speaking they should be extremely accurate, this has puzzled me to the point of disassembling more than a few crossbows to look for any mechanical defects that they could possibly have. The accuracy problem is not in the immediate mechanics of the crossbow itself it is only the human error factor.
A lot of research went into our crossbow accuracy study to identify it, throughout history up to modern crossbows we researched looking for possible obvious answers, after much study it is more than apparent that this issue had been dealt with in the historical past.
Some crossbows, this issue was cured by the simple installation of a sled which is a guide attached to the center of the crossbow bowstring to lessen string wear and insure exact centering of the string when cocking, the sled acted more as a exact nocking point much like that of a handbow.
Assuming you are using the correct arrow spine for your crossbow with the correct amount of fletching, with the correct F.O.C. and correct nock as suggested by the manufacturer of your crossbow, your crossbow should be extremely accurate "period".
There is one major cause of crossbow inaccuracy, spanning, thats it spanning, cocking the crossbow no matter how good you think you are doing it, if you have an accuracy issue, it is most likely when you cock your crossbow.
The severity of this problem was very noticable when I took various shooters to the range and allowed these individuals to cock and shoot a lot of various crossbows I had accrued for this study, the results were stunning, as to how very accurate crossbows went from tack drivers, to crossbows that wouldn't be good for any distant shot beyond 20 or so yards.
Fixing The Problem:
Now that I had identified the human error in crossbow accuracy and or inaccuracy it was time to find a fix for this problem that would work for all crossbow owners. A little more research started to reveal other fixes to this problem that was not apparent as a fix to the accuracy problem as they were fixes for using leverage to cock the crossbows of old.
Cocking an extremely high poundage crossbow was made easy through the use of various mechanical devices not only did these devices reduce the draw weight of the crossbow they also increased the accuracy as well.
For each .001 of an inch that the string is cocked from its exact center point will show some variation of accuracy loss down range, the further down range the more apparent the loss of accuracy becomes. On long range targets we were able to record very noticable accuracy losses.
While it may seem that this measuring down to the thousandths of an inch is a bit extreme, it was these measurements that were more able to tell us just how accurate a crossbow can be when cocked true and square. Using a bow square then adjusting the string after the crossbow was cocked, we were able to all but stack arrows on top of each other at 50 yards.
The odds of any cocking device to equal this much precision is not all that high, however we achieved better accuracy using a rope cocker as opposed to hand cocking and even better accuracy with crank cockers that were built into the crossbow as opposed to rope cockers.
Canting your crossbow to the right, in other words if the right limb of your crossbow is lower than the left one you have canted your crossbow to the right and will most likely shoot to the right and perhaps high or low depending on the distance you are shooting.
Canting your crossbow to the left, in other words if the left limb of your crossbow is lower than the right one you have canted your crossbow to the left and will most likely shoot to the left and perhaps high or low depending on the distance you are shooting.
For superior accuracy, install a level on your crossbow to stop canting but install it in such a way that it is easily visible to you while making your shot.
Crossbow Shooting High and Low, Gets Worse At Longer Ranges:
If you are using field points, the only way for this to happen is your arrows are not all the same weight, length or fletching is different length and or twist.
Crossbow Maintenance and Tuning For Accuracy:
Crossbow maintenance and tuning are very important factors when trying to maintain crossbow accuracy. Something as simple as 1 loose screw can destroy your crossbows accuracy, so here is a basic guide to crossbow tuning.
1. Thoroughly check for warn, loosened, damaged, or missing parts every time you use your crossbow.
2. Replace frayed or worn strings and cables, inspect the center serving on the string carefully looking for signs of extreme wear.
3. If excessive wear exists, it is a good idea to change the string and cables at the same time since they will all stretch over time, decreasing the crossbows performance.
4. Lubricate the flight track or rail, also known as the barrel, while shooting according to the crossbow manufacturers recommendations.
5. Wax the length of the crossbow string (except for the serving) and the cables according to the crossbow manufacturers recommendations.
6. All crossbows vibrate so make sure screws havenít worked their way loose through vibration. Always be careful not to overtighten screws and create a problem that you can not fix.
Crossbow Braced Height and Adjustment:
What is braced height?
Braced height is the distance between braced bowstring and belly side of riser, measured from the bowstring's center. In other words if you were to put a mark on the side of the flight track where the crossbow string is at rest you will notice over time that the string will slowly creep forward, this is normal as a new crossbow string slowly stretches and settles.
Tell-Tale Signs Of Braced Height Problems:
Your crossbow arrows will start impacting the target higher or lower than its previous years settings as the arrow velocity changes from string stretch. In some cases the velocity will be lower and some the velocity will be higher.
Crossbow Braced Height Adjustment:
Simply put, replace the string. With proper maintenance of the string and crossbow, the string should last a minimum of 150 shots, most will last well beyond that, to give years of service with only proper maintenance. Proper maintenance includes applying lubricant to the area where the string touches the flight track and keeping the flight track surface area free of all debris while shooting.
Crossbow Tiller and Adjustment:
What is tiller?
Tiller is the balance between the two limbs on the crossbow, both identical or nearly identical in pull weight and pull length.
Tell-Tale Signs Of Tiller Problems:
Your crossbow arrow will have wear marks on the arrow shaft from the groove in the flight track. Heavier marks on either shaft side will be an indication of tiller adjustment needs and this is even more evident on the rear or nock end of the arrow. Important Note: However this can also be a sign of you cocking your crossbow incorrectly as well. Both of these problems are evident when shooting your crossbow and your arrows are scattered left and right on the target.
How To Correctly Measure Tiller:
Measure from the point where the limb meets the prod housing back to the string. Do this on each side of the prod housing. If the measurement is not equal then the crossbow is out of till.
Compound Crossbow Tiller Adjustment:
Most compound crossbows have a tiller adjustment bolt on each of the limbs and correction is as simple as turning a bolt in or out to correct the tiller adjustment, further allowing extremely fine tuning of the crossbow.
Recurve Crossbow Tiller Adjustment:
Most recurve crossbows have but one recourse of action to correct severe tiller adjusment and that is to replace the limbs of the crossbow as a matched set.