Having trouble sighting in your crossbow? Here are some time-proven tips that will help keep it in tip-top shape and get you ready to practice more successfully this summer.
By Al Raychard
You just bought a crossbow and have had trouble sighting it in … or you’ve owned one for a few years but still can’t get the darn thing to shoot right? Frustrating! I know, because I’ve been there. Makes a guy want to throw up his hands and yell, “What in the world is going on?”
Today’s crossbows are highly efficient and viable hunting tools, but we tend to forget two things about them. First, whether recurve or compound, both crossbow designs are susceptible to human error and inconsistencies. Second, both styles are mechanical and are subject to wear and the riggers of time. As a result, crossbows require regular maintenance and, from time to time, occasional adjustments or replacement of parts. This is all necessary to achieve and maintain maximum performance and accuracy.
Three primary things including, including wheel or cam timing, the right arrows and string and cable maintenance, ensure consistent crossbow bolt flight and accuracy. As a crossbow enthusiast and hunter for nearly a decade, however, I know other factors also come into play.
Loose is of No Use
Crossbows are assembled using a variety of bolts and screws. The most important of the lot is the front-end mounting bolt used to fix the limb and riser assembly to the front of the rail. On some models, these same bolts also secure the cocking stirrup to the barrel.
Although lock washers are employed on some bows to keep these important bolts tight and in place, over time vibration can cause mounting bolts to loosen. Keeping that in mind, it should be part of every pre-shooting ritual to make sure these bolts are secure. The same is true of all other bolts and screws, including those holding the scope. One loose component can increase vibration and affect accuracy and arrow consistency.
The bolt (arrow) retention spring is one item that gets little attention until something goes wrong with it. In good working order — and when set properly — the retention spring should maintain enough down pressure to keep the arrow in place against the string and aligned on the flight rail. On most crossbows, the retention spring also works in conjunction with the anti-dry-fire and safety mechanisms.
A bolt that is not firmly set against the string will fly erratically and can be a real safety issue. The retention spring is an important component that should be checked regularly.
Typically, retention springs are fixed to the sight bridge by a screw. If the spring loosens, remove the scope and sight bridge and tighten the screw.
Today’s crossbows are extremely well made. With routine maintenance, a new crossbow should provide many years of reliable service. If accuracy problems or bolt inconsistencies arise, more times than not it is due to human error. I’ve worked with crossbow hunters for many years, and have concluded that, in most cases, crossbow accuracy problems begin and end with the shooter.
One of the most common errors occurs during the cocking process. In order for a crossbow bolt to shoot true each and every time, it is imperative the center serving be locked in the trigger mechanism in the same position every time. Cocking the string off center as little as 1/16-inch can put the bolt off target left or right by several inches by the time it travels 40 yards.
A simple fix is to put a mark on each side of the center serving where it crosses the flight rail when the string is at rest, providing a visual point to follow when cocking the bow. When the string is fully cocked, the marks should be in the same place on each side of the rail. If not, pulling back on the string and adjusting left or right will center it.
For bows without an integrated cocking system, cocking ropes and mechanical devices will greatly aid in cocking the serving center to the trigger mechanism. They also reduce the effort required to cock the bow, by as much as 50 percent in some cases.
Another human factor is “canting” — not holding the bow limbs level when shooting. If the right limb is lower than the left, the bolt will shoot right and perhaps high or low, depending upon the range. If the left limb is lower than the right, the bolt will shoot left and higher or lower. Make it a point to keep the limbs level; this is crucial to consistent crossbow accuracy.
Crossbows are also front-end heavy and difficult to hold in a shooting position for any length of time, especially while hunting. Sighting in from a shooting table and rifle rest (or bags) is the best option for dialing in a crossbow and achieving optimum arrow flight. When hunting, equip your stands with shooting rails, shooting sticks or a bipod. This will greatly improve your accuracy.
Several other human factors can affect consistent crossbow accuracy. The first is routine and religious maintenance — something too many hunters neglect. Rails, cables and all portions of the string except the center servings should be lubed and waxed every 25 to 30 shots.
Check your owner’s manual for recommended lubrication maintenance. It is crucial to maintain the trigger, center serving and dry-fire housing with a high-quality lubricant. You can use gun oil on the trigger to help prevent rust and stiff trigger pull.
Some manufacturers recommend changing strings and cables annually to maintain and ensure proper brace height and safety. With proper waxing and lubrication, strings and cables can last 150 shots or more, but over time strings and cables will stretch, allowing limbs to relax (creep). This will affect arrow speeds which, in turn, change the point of impact.
As a precaution — and to maintain optimum performance — strings and cables should be replaced as a unit at least every other year even if they appear to be in good condition.
To help gauge string wear on my crossbow, I use an indelible marker to draw vertical lines on each side of the rail where the string crosses at rest. If the string creeps past these marks, it is time to change it along with the cables.
Regardless of what anyone says, crossbows are not intended for long-range hunting. The short, heavy bolts lose velocity and energy much more quickly than arrows shot from compound bows. Always use a range-finder and restrict your shots at deer to less than 40 yards. This will help ensure better accuracy and lead to quick, clean kills.
Nothing beats practice. That means practicing with the same arrow and tip weight that you will use when hunting. Practice does indeed make perfect, and the more you know your crossbow, the more accurate and consistent you will shoot.
Spending time at the range to develop a proper trigger technique and shot sequence is important for hunting accuracy. A proper shot sequence — aim, click off safety, slowly and gradually squeeze the trigger, and follow through — can take 10 seconds or more. It takes practice to perform this consistently shot after shot. It’s that consistency that separates the really good hunters from the average ones.
The above preparations should put you on pace to pack bolts into tight groups each and every time you shoot your crossbow. Most of all, it should make you a deadly accurate hunter. If your accuracy suffers setbacks, it’s time to check your scope.
Bolt flight and accuracy can suddenly go awry when something as simple as a mount screw comes loose, or the scope merely gets bumped. Just as important, the horizontal cross-hairs must be perfectly parallel across the flight rail. If the scope has multi-dots, the dots must be perfectly vertical.
To assure proper alignment, mount the crossbow in a padded vice, making sure the flight rail is horizontally level. Mount the scope and snug it down. Against a far wall, attach a target with a cross-hair, making sure the horizontal line is level and the cross-hair line is perfectly vertical. Look through the scope and match the horizontal line or vertical dots with the appropriate line on the target. When it is, tighten the scope. The scope is now mounted true to mechanical center.
After windage and elevation adjustments at the range per manufacturer’s recommendations, the crossbow should shoot quarter-sized groups or better out to 30 yards.
All manufacturers recommend specific bolts for their crossbows and, in many cases, different bolts for different models. Whether made of aluminum or carbon, arrows are chosen based on several factors, including overall weight, spine, straightness and nock-to-vane length. To achieve and maintain optimum accuracy, only use bolts recommended by the manufacturer.
Other problems can arise with cam timing and tiller alignment. This is most evident on older compound crossbows. Over time, improper cam synchronization dramatically alters arrow flight. Look for wear marks on either side of the arrow shaft, especially near the nock, made by poor alignment with the flight track. Another indication is if bolt flight is consistently left or right of the intended point of impact.
These symptoms, however, can also indicate improper cocking practices, so be sure you are cocking the bow properly. To check the cam timing, most compound crossbows have timing lines, holes or dots in each cam. If not, measure each side of the bow from where the limbs meet the prod housing to the string.
In either case, these indicators or measurements should be equal indicating identical or near identical pull weight and pull length. If not, the bow is “out of till.” Most models have an adjustment bolt on each limb and adjustment is made by turning the bolt in or out to adjust the tiller and synchronize the cams. On recurve crossbows, the only course of action is to replace the limbs with a new set.
Accurizing a crossbow and maintaining consistent accuracy is not difficult. It just takes some understanding of basic concepts, the patience to do things right and a commitment to keeping your crossbow in tip-top condition.
— Al Raychard is a veteran deer hunter from Maine.