Can Regular Rifle Scopes Be Used on a Crossbow?
Crossbows are becoming a popular option for hunting. In most states, crossbows can be used during general big game seasons where rifles, shotguns, or straight wall cartridges are allowed. With crossbows becoming a more common option, many hunters would like to know if they can use a rifle scope on a crossbow.
Rifle scopes can be used successfully on crossbows, provided that the scope is a quality optic that can handle multi-directional ‘recoil’ and has features such as adjustable parallax under 100 yards.
As we’ll examine, there are some caveats that crossbow owners should be aware of if they intend to put a rifle scope on their bow. While the two weapons have similarities, a crossbow is not a firearm. The crossbow is a complex weapon that is as old as gunpowder, and much older than the handheld firearms that we recognize today as ‘guns’.
The Modern Crossbow
The 21st Century hunting crossbow has many upgrades over their predecessors, including compound limbs and built-in string drawing mechanisms. Quality crossbows are precision machines that can be as accurate as any rifle out to 100 yards. Simply put, modern crossbows are an excellent weapon for use in close-quarters hunting situations.
The advantages of a 21st century crossbow are many:
- Crossbows are much quieter than firearms and do not require hearing protection.
- Compared to a compound bow, crossbows have more speed and hit much harder.
- The learning curve for a crossbow is not nearly as steep as learning a traditional bow.
- Crossbows are incredibly accurate, capable of rifle-like group sizes (1 MOA).
- They can be flexibly used in some states for both firearms and archery season.
These are just some of the advantages a hunter will appreciate from a crossbow. Like any type of weapon, there are some drawbacks. Most notably, reload time is slow and while they have impressive range, crossbows can’t compete with rifles. Also, the cost of a quality crossbow is similar to that of higher-end hunting rifles. Hunters should expect to shell out at least $1000 for a good hunting model.
One thing crossbows require to be effective as a weapon for hunting are quality sights. Open sights are available and some people certainly prefer that for shooting at close range, but most hunters will be better served with a scope.
Rifle vs Crossbow Recoil
Quality rifle scopes are far more numerous compared to crossbow scopes. Not to mention most rifle shooters have a scope or two laying around. Therefore its natural to ask, ‘can a rifle scope be used on a crossbow?’
The short answer is ‘yes’, but there is one major issue to consider.
Crossbows do not have the same sort of recoil as a rifle. Both rifles and crossbows have a rear-ward recoil, which by itself isn’t much of an issue. When the bullet from a rifle or the bolt from a crossbow are shot forward, there is going to be an equal and opposite force pushing backward, it’s basic physics. The rearward recoil of a crossbow is significantly less compared to the typical center fire hunting rifle.
So a rifle scope will work then, right? Well, not always. You see, unlike a rifle, crossbows have limbs. These limbs hold potential energy that is imparted onto the bolt when the trigger is pulled. For that to happen, those limbs will move forward, again causing an equal amount of force rearward. However, unlike the bolt, the limbs have to stop moving after a few inches.
Since the limbs have mass, they carry momentum when moving forward. Momentum is basically an object’s resistance to change in velocity, so when the limbs stop moving forward, that momentum is carried through the limbs to the body of the weapon. Basically, the weapon wants to move forward once the limbs stop moving after the bolt has been released.
This all happens in a fraction of a second, but the result is that a crossbow has two stages of ‘recoil’ energy. The first is directed rearward, like a rifle, and the second is directed forward, like a bow. While the felt recoil energy isn’t as bad as a rifle, not all scopes are designed to handle recoil forces in multiple directions. Some rifle scopes therefore can break under the unique forces of a crossbow.
Rifle Scope Requirements for Crossbows
The good news is that there are plenty of rifle scopes on the market which can handle crossbows. Quality optics from brands such as Leupold and Vortex should be capable to holding up to the recoil forces generated by a crossbow. An easy way to tell is if a scope is rated for handguns, shotguns, and air rifles in addition to centerfire rifles. Such a scope has been designed for a variety of weapons.
There are other requirements to consider besides the engineering of the scope, which should narrow down the options significantly. To be an effective on a crossbow, a rifle scope should have the following features:
- Close range parallax adjustment or a fixed parallax under 100 yards (50 is ideal).
- Reticle with multiple elevation and windage marks such as BDC reticles.
- Low power range such as 1-4x, 2-7x variable or 4x, 2.5x fixed.
- Adjustable crosshair focus (sometimes combined with parallax adjustment)
A rifle scope that has all these features and is rated for different types of weapons will almost certainly be a good option for a crossbow. Even then, it is important to ask the manufacturer of the scope if it will work on a crossbow. Some brands, such as Vortex, make crossbow variants of some of their rifle scopes. This is probably the best option if dedicated crossbow optics are off the table.
All that being said, the one drawback that every rifle scope will have on a crossbow is the inability to adjust for different bolt speeds and/or weights. A crossbow with a rifle scope will have to be calibrated to a specific bolt speed and weight, changing either would result in a drastically different zero range. The photo below shows a crossbow scope with a velocity dial to adjust for different bolt speeds.
Some hunters do indeed put rifle scopes on their crossbows, so it has been proven to be possible. Whether the scope you choose will do the job or not is a different matter. The good news is that the multi-directional recoil of a crossbow is not terribly forceful so quality optics designed for different weapon systems are most likely up to the task.
However, that doesn’t mean a rifle scope is that great of a choice, let alone the ideal choice. The reason is pretty simple, crossbows and rifles are not the same. Not only that, but if someone is shelling out over $1000 for a quality crossbow, why hamper it’s effectiveness by using an optic that’s not meant for the task? Basically, a rifle scope can be used on a crossbow but there are some better options out there.
My recommendation is to get a purpose-built sight or optic meant for crossbows. They will be designed for the weapon and will improve it’s usability. My suggestions for crossbow optics would be to either try an actual crossbow scope or a red dot. Either one will likely give better results than the rifle scope that’s been sitting on the shelf waiting for the right gun.